[wasm][debugger] Support "on frame evaluation" of functions returning char (#65842)

[wasm][debugger] Support "on frame evaluation" of functions returning char (#65842)

* Optional parameter fix.

* Working version of optional parameter support, requires refactoring.

* Refactored.

* Fixed failing tests.

* Add support to functions returning char, add test to an existing case.

* Simplified tests.

* Merged with optional params, uncommented char test

* Remove spaces.

* Applied @radical's suggestions.

* Removed indentation.

* Another indentation.

* Removed comment.

* Reverted type=char, as @radical suggested.

* Applied @radical's suggestions. No need for escaping + reverting original name.