[llvm] [GlobalIsel] combine extract vector element (PR #91922)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

https://github.com/llvm/llvm-project/blob/61d4ca872215d3dfff0b3c92151dcbdc546a0aab/llvm/test/CodeGen/AArch64/extract-vector-elt.ll#L483

The tricky case with an ext in between.

https://github.com/llvm/llvm-project/pull/91922