[6.0] Fix renaming enum case parameters with unnamed associated arguments

[ahoppen]

• Explanation: We treated enum case parameters the same way as function parameters and weren’t considering that they can be unlabeled. That caused us to insert eg. _ in front of the case’s type, producing case myCase(_ String), which is invalid. Report enumCaseParameters as a special parameter kind so that sourcekitd can work with it.
• Scope: Rename in SourceKit
• Risk: Low, only affects rename of enum cases
• Testing: Added test cases
• Issue: rdar://127646036 / https://github.com/apple/sourcekit-lsp/issues/1228
• Reviewer: @hamishknight on https://github.com/apple/swift-syntax/pull/2678

[ahoppen]

https://github.com/apple/swift/pull/74534 https://github.com/apple/sourcekit-lsp/pull/1482

@swift-ci Please test

[ahoppen]

https://github.com/apple/swift/pull/74534 https://github.com/apple/sourcekit-lsp/pull/1482

@swift-ci Please test macOS