[NFC][DirectX] Clean-up `llvm-objcopy` to be consistent across implementation details (#177006)
This change is to ensure the implementation of the various
`llvm-objcopy` args are implemented with consistent patterns.
This is intended to help have a clear and consistent point of reference
for new contributors to extend `llvm-objcopy`.
These changes are largely to propagate the review comments of
https://github.com/llvm/llvm-project/pull/159999 back onto the changes
introduced before it.