[AArch64] Enhance bit-field-positioning op matcher to see through 'any_extend' for...

[AArch64] Enhance bit-field-positioning op matcher to see through 'any_extend' for pattern 'and(any_extend(shl(val, N)), shifted-mask)'

Before this patch (and refactor patch D135843), isBitfieldPositioningOp won't handle "and(any_extend(shl(val, N), shifted-mask)" (bail out if AND op is not SHL)

After this patch, isBitfieldPositioningOp will see through "any_extend" to find "shl" to find possible bit-field-positioning nodes.

https://gcc.godbolt.org/z/3ncGKbGW6 is a four-liner LLVM IR that could be optimized to UBFIZ (see added test case test_and_extended_shift_with_imm in llvm/test/CodeGen/AArch64/bitfield-insert.ll). One existing test case also improves.

Differential Revision: https://reviews.llvm.org/D135852