[red-knot] Add support for the LSP diagnostic tag

[ercbot]

Summary

closes #17536

• Adds DiagnosticTag enum { Unnecessary, Deprecated } and a tags fields to the Annotation struct in the ruff diagnostics system
• Updates the to_lsp_diagnostic function to include conversion from the above tags to LSP Diagnostic Tags.

Note: doesn't update any existing code to use the tags, just wires it up for future implementation

Test Plan

Existing tests have passed, seeking guidance on where to add new tests for this if necessary

[github-actions]

mypy_primer results

No ecosystem changes detected ✅

[MichaReiser]

Nice!

Existing tests have passed, seeking guidance on where to add new tests for this if necessary

We don't really have tests for our diagnostic conversion code. So I thinkit's fine to skip automated tests and instead test this manually (you can change an arbitrary diagnostic to add the DEPRECATED or UNNECESSARY tag)

[BurntSushi]

LGTM

[MichaReiser]

This is great. Would you mind adding a test plan to your PR summary? What I do for features like this is that I record a screen recording demonstrating the feature in VS code.

This will require adding the tag to at least one emitted diagnostic.

[dhruvmanila]

If you're using VS Code, you can use the existing Ruff extension to test out the red-knot server by updating ruff.path to point to the red_knot binary:

{
	"ruff.path": ["/path/to/red_knot"]
}

[MichaReiser]

I went ahead and rebased this PR, added methods to set the tags on Diagnostic and tested that the tag is propagated to the client by adding it to DIVISION_BY_ZERO (see how the code is now grayed out in VS code)