Fix #2430: Hide 'Convert to computed property' for Void functions

[DPrakashhh]

Summary
This PR resolves issue #2430 by preventing the "Convert to computed property" code action from being suggested for functions that do not return a meaningful value. Converting a function with no return value to a computed property is semantically incorrect and results in nonsensical refactoring.

Changes
1-Logic Enhancement: Updated SyntaxRefactoringCodeActionProvider.swift to include a guard statement that checks for void return types before offering the refactoring.
2-Void Detection Helper: Added a private "isVoidReturnType" helper that robustly identifies:
2.1-Implicit Void: Functions with no return clause.
2.2-Explicit Void: Functions returning Void.
2.3-Empty Tuples: Functions returning ().
3-Normalization: Used whitespace filtering to ensure the check is resistant to formatting variations like -> Void or -> ( ).
4-Regression Tests: Added three comprehensive test cases to CodeActionTests.swift to ensure these scenarios are permanently covered.

Verification Results
1-Automated Tests: Ran swift test --filter CodeActionTests. All 37 tests passed, including the new negative test cases.
2-Manual Verification: Confirmed in VS Code that the refactoring lightbulb is correctly hidden for func test() {} but remains available for functions with actual return types like func test() -> String.

Open for any changes :)

[DPrakashhh]

On it :)

[DPrakashhh]

Thanks for the feedback, I have updated the PR with a new commit that switches to the TypeSyntax extension logic you suggested. I also cleaned up the guard bindings and refactored the tests to use assertCodeActions to keep things concise. Ready for another look!

[ahoppen]

Just some leftover code, otherwise looks good to me 👍🏽

[DPrakashhh]

Done!

[ahoppen]

Nice, let’s get it in.

[ahoppen]

@swift-ci Please test

[ahoppen]

@swift-ci Please test Windows

[DPrakashhh]

Thank you! for merging it :D