[llvm] [NFC] Separate UnwindTable from DebugFrame into a different type (PR #142521)

[David Blaikie via llvm-commits]

dwblaikie wrote:

@Sterling-Augustine is this part of your DWARF expression parsing work? Or coincidentally overlapping with it?

@amsen20 where do you plan to put this code once it is refactored? Into MC itself, elsewhere, some new library?

https://github.com/llvm/llvm-project/pull/142521