[clang] [flang] [flang] Add support for -f[no-]verbose-asm (PR #130788)

[Tarun Prabhu via cfe-commits]

https://github.com/tarunprabhu commented:

Do we really want to maintain an equivalence with clang by keeping this in `CodeGenOptions` when it really ought to be a `TargetOption`? It looks like almost all of the handling of this option takes place in `flang`, so we probably shouldn't be bound to idiosyncracies in `clang` if we can help it.

It might make the option declaration messier unless conditional marshalling is possible (I don't know if it is or not). 

I don't have a very strong opinion on this. If others are ok with leaving this in `CodeGenOptions`, I'm happy to go along with it. What do you think?

https://github.com/llvm/llvm-project/pull/130788