[mlir] Fix --convert-func-to-llvm=emit-c-wrappers argument and result attribute handling

When using `--convert-func-to-llvm=emit-c-wrappers` the attribute arguments of the wrapper would not be created correctly in some cases.
This patch fixes that and introduces a set of tests for (hopefully) all corner cases.

See https://github.com/llvm/llvm-project/issues/53503

Author: Sam Carroll <sam.carroll@lmns.com>
Co-Author: Laszlo Kindrat <laszlo.kindrat@lmns.com>

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D119895