[LLD][COFF] Add -build-id flag to generate .buildid section. (#71433)

[RFC](https://discourse.llvm.org/t/rfc-add-build-id-flag-to-lld-link/74661)

Before, lld-link only generate the debug directory containing guid when
generating PDB with the hash of PDB content.

With this change, lld-link can generate the debug directory when only
`/build-id` is given:
1. If generating PDB, `/build-id` is ignored. Same behaviour as before.
2. Not generating PDB, using hash of the binary.
   - Not under MinGW, the debug directory is still in `.rdata` section.
   - Under MinGW, place the debug directory into new `.buildid` section.