[clang] [flang] Add flags controlling whether to run the fir alias tags pass (PR #68595)

[Tom Eccles via cfe-commits]

tblah wrote:

> Does `falias-analysis` control the existing TBAA generation as well?

Not in this patch while -falias-analysis is kept separate and non-default. But that will be the intention in the future.

https://github.com/llvm/llvm-project/pull/68595