[llvm] [GISEL][RISCV] Add G_VACOPY GISEL opcode and add lowering code for it. (PR #73066)

[Michael Maitland via llvm-commits]

michaelmaitland wrote:

> I think every generic intrinsic and instruction should have a defined G_* opcode and not route through G_INTRINSIC*. G_INTRINSIC* is for target intrinsics

I agree. Are you okay with going through G_INTRINSIC* for this patch and then we can move all targets to G_VACOPY in a future patch?

https://github.com/llvm/llvm-project/pull/73066