Fix switch-case statements with mismatching types

[aleino-nv]

When trying to resolve shader-slang/slang#4921 with commit shader-slang/slang@a32156e, I noticed that there are some cases where the types of switch conditions and the corresponding case expressions have mismatching types (enums in case expression and uint in case condition).

Cherry-picking shader-slang/slang@a32156e and launching CI should be enough to reproduce the issues.