[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Andrzej Warzyński via cfe-commits]

https://github.com/banach-space approved this pull request.

LGTM, thanks for working on this and for addressing my comments 🙏🏻 

https://github.com/llvm/llvm-project/pull/90886