Update analyze tool to use LSP, simplify tool

[jakemac53]

• Use dart language-server for errors, file watching, etc.
• Drop analyzer dependency.
• Depends on language_server_protocol package from the SDK using a git dependency for now:
  • We can fix this by moving into the SDK
  • Or publishing language_server_protocol
• The tool now just always returns all errors for all known workspaces.
• Errors are returned in a structured format right now instead of as a human readable string.
• We might want to steal some code from analyzer/DartCode etc to get a human readable string going.
• Or if this is just for AI input, structured may even be better.

In the future, we might try to use the DTD connection to talk, which won't change this code too much. But right now DTD has very limited support (read/write properties).

Closes #65 as well

[github-actions]

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[kenzieschmoll]

LGTM, but would be good to wait for @bwilkerson's review as well.

[bwilkerson]

I'm guessing that the analysis server must already have some similar code. At some point we should look at sharing the implementation.

[jakemac53]

Yeah I would probably move it to be a part of the language_server_protocol package.