[lld] [ELF] Move target-specific synthetic sections into Arch/ files (PR #184057)

[Peter Smith via llvm-commits]

https://github.com/smithp35 commented:

Thanks for putting this together, it should help remove some of the visual noise of the target specific code.

One small suggestion about naming and a comment.

Possibly worth splitting out the small number of source changes such as moving the struct/class into a separate commit. That will make it easier to see that the code is just being moved and not changed.

https://github.com/llvm/llvm-project/pull/184057