Enhancement: Re-design alerts

[parmesant]

Description

Alerts used to be linked to a logstream and were based on an expression based logic With this PR, alerts will be independent of logstreams and will be based on a SQL query The given threshold config will get evaluated against the result of the query and the target config will be used to send out notifications

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TODO:

• Unit tests
• Merge target notification task with Alerts

This PR has:

• been tested to ensure log ingestion and log query works.
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added documentation for new or modified features or behaviors.

[coveralls]

Pull Request Test Coverage Report for Build 12511034600

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 661 (0.0%) changed or added relevant lines in 14 files are covered.
• 83 unchanged lines in 7 files lost coverage.
• Overall coverage decreased (-1.2%) to 10.325%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/handlers/http/logstream.rs	0	1	0.0%
src/handlers/airplane.rs	0	2	0.0%
src/cli.rs	0	3	0.0%
src/rbac/role.rs	0	3	0.0%
src/query/mod.rs	0	7	0.0%
src/handlers/http/modal/query_server.rs	0	10	0.0%
src/storage/object_storage.rs	0	18	0.0%
src/handlers/http/query.rs	0	29	0.0%
src/handlers/http/modal/server.rs	0	36	0.0%
src/sync.rs	0	46	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/alerts/mod.rs	1	0.0%
src/event/mod.rs	1	0.0%
src/storage/object_storage.rs	2	0.0%
src/metadata.rs	2	1.42%
src/rbac/role.rs	2	0.0%
src/alerts/target.rs	4	0.0%
src/option.rs	71	0.0%

Totals
Change from base Build 12465451984:	-1.2%
Covered Lines:	1845
Relevant Lines:	17870

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💛 - Coveralls

[nitisht]

Please address the conflicts