Depends on https://github.com/swiftlang/swift/pull/83378
---
Adds support for the LSP signature help request.
> [!NOTE]
> As of https://github.com/swiftlang/swift/pull/83378, SourceKitD still
doesn't separate parameter documentation from the signature
documentation and thus parameters don't have their own separate
documentation. This should just work once SourceKitD implements this
functionality and we'll only need to modify the tests.
