[clang] [flang] [flang][driver] add -flang-deprecated-no-hlfir hidden option (PR #71820)

[Tom Eccles via cfe-commits]

https://github.com/tblah requested changes to this pull request.

Thanks for this!

Please could you also add testing in flang/Driver/frontend-forwarding.f90, flang/test/HLFIR/hlfir-flang.f90

https://github.com/llvm/llvm-project/pull/71820