[llvm] [llvm-objcopy] Add llvm-objcopy option --ignore-symbol (PR #80873)

[James Henderson via llvm-commits]

https://github.com/jh7370 requested changes to this pull request.

I think many of the same comments I made in #80872 apply equally well to this PR, so I'm not going to list them all out here too. Please address them in this PR, and then I'll come back and review again

https://github.com/llvm/llvm-project/pull/80873