[DO NOT MERGE] Create New Tool LGgen

[haocheng-han]

Complete Issue #1235, create a new command line tool LGgen, now supports generating C#/TS variants.

Run the Tool

using commands like
dotnet LGgen.dll [-l cs/ts] [-n CLASS_NAME] [-c] [-i LG_FILE_PATH] [-o OUTPUT_PATH]
-l cs/ts : Select C# or Typescript, default to C#.
-i : LG file path or folder.
-o : Output path, defaults to directory where LG file is and the same name with LG file
-n : Designate class name, defaults to the same name of LG file
-c : Grammar check mode. You only need to input [-c] [-i LG_FILE_PATH] to run the grammar check.

Test

In LGgen_test, several usages are tested.

[cleemullins]

The LG CLI isn't ready for merging into master. Please reach out to me via email and lets sync.

[vishwacsena]

This should get folded under the broader cli consolidation and should be part of the all up LG solution and should not go into master.

@cleemullins could we get this over to Jonathan since he is tracking the LG CLI effort?

[sgellock]

@M-Gustuf thanks for the PR. There are a couple of things that need to be addressed before we can consider this. One this PR is against master. This tool is not yet in master and should be made against V.next. The second issue is this is written in C#. All CLI tooling needs to be written in JS or TS. I'm closing this PR out as I will assume you or someone from your team will issue a new PR