[clang] [CIR][AArch64] Implement vget_lane_bf16 and vgetq_lane_bf16 builtins (PR #186866)

[Andrzej Warzyński via cfe-commits]

banach-space wrote:

> Hello @banach-space , I just wanted to ask if you saw this PR. Several later PRs were added to the table so I don't want this to be accidentally skipped

Thanks for the ping and apologies, this has sadly slipped off my radar :( Thank you @tblah for adding me as a reviewer!

https://github.com/llvm/llvm-project/pull/186866