[lld] [LLD][COFF] allow saving intermediate files with /lldsavetemps (PR #115131)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> @mstorsjo Was there anything still pending before this is can merged?

Ah, sorry about that; no, I usually just don't merge right away, in case someone else wanted to comment on it, but I forgot to get back to merging it. I'll do it now.

https://github.com/llvm/llvm-project/pull/115131