Switch generated mappers to pointer-based signatures and add tests

[hacks1ash]

Description

• Updated all generated mapper functions to use pointer-based signatures for improved nil safety and consistent behavior.
• Added a test case to handle disambiguation of function names when internal and external types share identical names.

Testing

• Tests added/updated as necessary.
• Verified correct disambiguation of function names.
• Ensured no regressions in mapper function functionality.

Checklist

• Documentation updated if applicable.
• All tests passing.