fix: 'Go to symbol' now includes methods inside a class

[Karman-singh15]

Summary

Logic was added to post-process symbols inside a ClassDef.
it allows Stmt::FunctionDef to remain simple (always creating a FUNCTION), and shifts the responsibility of context-awareness (knowing it is a method) to the parent ClassDef.
Any child symbol with SymbolKind::FUNCTION is now converted to SymbolKind::METHOD

Fixes #2051

Test Plan

I updated the existing test
test_document_symbols_normal_file in pyrefly/lib/test/lsp/lsp_interaction/document_symbols.rs
The test uses an existing file normal.py which contains NormalClass and normal_method.
I updated the test assertion to verify that normal_method inside NormalClass has SymbolKind::METHOD.

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[stroxler]

Thanks for the PR! Looks good to me, I'll try to get a second review and merge in the next day or two

Heads up that the red CI signal is just format, you can run cargo fmt to avoid it in the future but I can patch it up so no need to worry about it on this commit

[meta-codesync]

@stroxler has imported this pull request. If you are a Meta employee, you can view this in D90689263.

[grievejia]

Review automatically exported from Phabricator review in Meta.

[meta-codesync]

@stroxler merged this pull request in 159c5c3.