[clang] [CIR][AArch64] Support BF16/FP16 NEON types and lower vdup lane builtins (PR #187460)

[Andrzej Warzyński via cfe-commits]

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banach-space wrote:

>From what I can tell, there won't be anything left after this PR, so this comment can be deleted.
```suggestion
```

https://github.com/llvm/llvm-project/pull/187460