[clang] [llvm] [LLVM][SROA] Teach SROA how to "bitcast" between fixed and scalable vectors. (PR #130973)

[Min-Yih Hsu via cfe-commits]

mshockwave wrote:

> @pawosm-arm - I've removed the reviewers because it is not quite ready yet. I need to investigate the potential regressions shown by the RISCV tests.

you can also turn this PR into a draft if you want

https://github.com/llvm/llvm-project/pull/130973