lsp: tracking issue for code actions features

[llllvvuu]

There are a couple of LSP features that I found harder than I expected to implement (and I am not a heavy user of these features), but if anyone happens to read this and enjoy the challenge, they are:

1. Quickfix: Fix only the selected lint. Here's a template for how one might edit lsp.py (the TODO is the hard part):

def diagnostic_generator(
    self, uri: str, autofix: bool = False
) -> Optional[Generator[Result, bool, Optional[FileContent]]]:
    # ... existing code ...
    for result in generator:
        violation = result.violation
        if not violation:
            continue
        diagnostic = Diagnostic(
            # ... existing fields ...
            code=violation.rule_name,
            source="fixit",
            data={
                "fix": # TODO: convert violation.replacement, a CSTNode, to a replacement string
            },
        )
        diagnostics.append(diagnostic)
    # ... existing code ...

def code_action(self, params: CodeActionParams) -> List[CodeAction]:
    uri = params.text_document.uri
    diagnostics = params.context.diagnostics
    actions = []

    for diagnostic in diagnostics:
        if "fix" in diagnostic.data:
            fix = diagnostic.data["fix"]

            action = CodeAction(
                title=f"Fix: {diagnostic.code}",
                kind=CodeActionKind.QuickFix,
                edit=WorkspaceEdit(
                    changes={
                        uri: [
                            TextEdit(
                                range=diagnostic.range,
                                new_text=fix,
                            )
                        ]
                    }
                ),
            )
            actions.append(action)

    return actions

2. Insert ignore comment: The hard part here is figuring out where to insert the comment.

For context, the code actions menu is the menu that comes from a light bulb next to the yellow squiggly under a lint issue. A good example of an extension that has this is the ESLint extension (built-in to VSCode I believe). Ruff also has these features, although I'm sure their model is very different so I'm not sure how easy it is to take inspiration.