Add type anotations everywhere

[cereal2nd]

a mypy run results in a lot of errors, we should solve all these:

helpers.py:26: error: Incompatible return value type (got "bool", expected "Dict[Any, Any]")
helpers.py:65: error: Need type annotation for "result" (hint: "result: Dict[, ] = ...")
helpers.py:97: error: Argument 1 to "join" has incompatible type "Optional[str]"; expected "Union[str, PathLike[str]]"
command_registry.py:12: error: Need type annotation for "_default_commands" (hint: "_default_commands: Dict[, ] = ...")
command_registry.py:13: error: Need type annotation for "_overrides" (hint: "_overrides: Dict[, ] = ...")
command_registry.py:16: error: Incompatible default for argument "module_name" (default has type "int", argument has type "str")
command_registry.py:30: error: Argument 3 to "_register_override" of "CommandRegistry" has incompatible type "Optional[Any]"; expected "str"
command_registry.py:71: error: Incompatible default for argument "module_type" (default has type "int", argument has type "str")
message.py:42: error: Incompatible types in assignment (expression has type "int", variable has type "None")
message.py:43: error: Incompatible types in assignment (expression has type "int", variable has type "bool")
message.py:69: error: Incompatible types in assignment (expression has type "int", variable has type "None")
message.py:130: error: Incompatible return value type (got "List[int]", expected "str")
handler.py:48: error: Unsupported operand types for & ("str" and "int")
handler.py:49: error: Unsupported operand types for & ("str" and "int")
handler.py:61: error: Incompatible types in assignment (expression has type "ModuleSubTypeMessage", variable has type "ModuleTypeMessage")
handler.py:74: error: Argument 1 to "get_command" of "CommandRegistry" has incompatible type "str"; expected "int"
handler.py:75: error: "None" not callable
handler.py:97: error: Need type annotation for "result" (hint: "result: Dict[, ] = ...")
handler.py:99: error: Incompatible types in assignment (expression has type "str", variable has type "int")
handler.py:147: error: "Message" has no attribute "module_type"
handler.py:149: error: "Message" has no attribute "module_type"
handler.py:154: error: "Message" has no attribute "module_type"
handler.py:156: error: "Message" has no attribute "memory_map_version"
handler.py:157: error: "Message" has no attribute "build_year"
handler.py:158: error: "Message" has no attribute "build_week"
handler.py:159: error: "Message" has no attribute "serial"
handler.py:166: error: "Message" has no attribute "sub_address_1"
handler.py:167: error: "Message" has no attribute "sub_address_2"
handler.py:168: error: "Message" has no attribute "sub_address_3"
handler.py:169: error: "Message" has no attribute "sub_address_4"
handler.py:182: error: Unsupported operand types for & ("str" and "int")
channels.py:169: error: Incompatible return value type (got "int", expected "str")
channels.py:172: error: Incompatible return value type (got "None", expected "str")
channels.py:189: error: "None" not callable
channels.py:195: error: "None" not callable
channels.py:201: error: "None" not callable
channels.py:207: error: "None" not callable
channels.py:261: error: "None" not callable
channels.py:312: error: Incompatible return value type (got "None", expected "str")
channels.py:313: error: Incompatible return value type (got "None", expected "str")
channels.py:316: error: Unsupported left operand type for / ("None")
channels.py:319: error: Incompatible return value type (got "None", expected "str")
channels.py:366: error: "None" not callable
channels.py:377: error: "None" not callable
channels.py:409: error: Incompatible return value type (got "None", expected "int")
channels.py:414: error: Incompatible return value type (got "None", expected "int")
channels.py:478: error: Incompatible return value type (got "None", expected "bool")
channels.py:494: error: "None" not callable
channels.py:503: error: "None" not callable
channels.py:524: error: "None" not callable
channels.py:531: error: "None" not callable
module.py:90: error: Need type annotation for "_name" (hint: "_name: Dict[, ] = ...")
module.py:91: error: Need type annotation for "_sub_address" (hint: "_sub_address: Dict[, ] = ...")
module.py:97: error: Need type annotation for "_channels" (hint: "_channels: Dict[, ] = ...")
module.py:167: error: Incompatible return value type (got "Dict[Any, Any]", expected "str")
module.py:260: error: Argument 1 to "_translate_channel_name" of "Module" has incompatible type "int"; expected "str"
module.py:267: error: Argument 1 to "_translate_channel_name" of "Module" has incompatible type "int"; expected "str"
module.py:276: error: Argument 1 to "_translate_channel_name" of "Module" has incompatible type "int"; expected "str"
module.py:304: error: Argument 1 to "_translate_channel_name" of "Module" has incompatible type "int"; expected "str"
module.py:319: error: Argument 1 to "_translate_channel_name" of "Module" has incompatible type "int"; expected "str"
module.py:324: error: Argument 1 to "_translate_channel_name" of "Module" has incompatible type "int"; expected "str"
module.py:329: error: Argument 1 to "_translate_channel_name" of "Module" has incompatible type "int"; expected "str"
module.py:334: error: Argument 1 to "_translate_channel_name" of "Module" has incompatible type "int"; expected "str"
module.py:358: error: Incompatible return value type (got "Dict[Any, Any]", expected "List[Any]")
module.py:420: error: Incompatible types in assignment (expression has type "str", variable has type "Dict[Any, Any]")
module.py:509: error: Incompatible types in assignment (expression has type "None", variable has type "Dict[Any, Any]")
discovery.py:15: error: Argument 1 of "connection_made" is incompatible with supertype "BaseProtocol"; supertype defines the argument type as "BaseTransport"
discovery.py:15: note: This violates the Liskov substitution principle
discovery.py:15: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
controller.py:11: error: Skipping analyzing "serial": found module but no type hints or library stubs
controller.py:11: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
controller.py:12: error: Skipping analyzing "serial_asyncio": found module but no type hints or library stubs
controller.py:38: error: Need type annotation for "_modules" (hint: "_modules: Dict[, ] = ...")
controller.py:39: error: Need type annotation for "_submodules" (hint: "_submodules: List[] = ...")
controller.py:40: error: Need type annotation for "_send_queue"
controller.py:41: error: Need type annotation for "_tasks" (hint: "_tasks: List[] = ...")
controller.py:65: error: Argument 1 to "Module" has incompatible type "str"; expected "int"
controller.py:66: error: Argument 2 to "Module" has incompatible type "str"; expected "int"
controller.py:85: error: Missing return statement
controller.py:117: error: "None" has no attribute "close"
controller.py:118: error: "None" has no attribute "wait_closed"
controller.py:132: error: Incompatible types in assignment (expression has type "None", variable has type "SSLContext")
controller.py:134: error: Incompatible types in assignment (expression has type "StreamReader", variable has type "None")
controller.py:134: error: Incompatible types in assignment (expression has type "StreamWriter", variable has type "None")
controller.py:217: error: "None" has no attribute "write"
controller.py:228: error: "None" has no attribute "read"