feat: Fix up syntax errors in attribute macro inputs to make completion work more often

[flodiebold]

This implements the "fix up syntax nodes" workaround mentioned in #11014. It isn't much more than a proof of concept; I have only implemented a few cases, but it already helps quite a bit.

Some notes:

• I'm not super happy about how much the fixup procedure needs to interact with the syntax node -> token tree conversion code (e.g. needing to share the token map). This could maybe be simplified with some refactoring of that code.
• It would maybe be nice to have the fixup procedure reuse or share information with the parser, though I'm not really sure how much that would actually help.

[flodiebold]

Proof that it works:

[Veykril]

I'm not super happy about how much the fixup procedure needs to interact with the syntax node -> token tree conversion code (e.g. needing to share the token map). This could maybe be simplified with some refactoring of that code.

Ye I agree, this interaction seems rather difficult to get behind. I hope there is some cleanup we can do here.

[flodiebold]

@Veykril any objections to merging it in the current state though?

[Veykril]

No objections here,

one thing to note as the fixup stuff is only really relevant for completions, I am not too fond of the fixup stuff being generated for all other macro expansion query calls that aren't interested in it(though this probably is a non-issue)
Forget this comment we do need it for everything probably(due to diagnostics etc)

[flodiebold]

We do need the fixup for the expansion during normal analysis even for completions anyway, since we (currently) can't do things like name resolution inside the speculative expansion.

bors r+

[bors]

Build succeeded:

• Rust (macos-latest)
• Rust (ubuntu-latest)
• Rust (windows-latest)
• TypeScript (ubuntu-latest)
• TypeScript (windows-latest)