[X86] MatchVectorAllZeroTest - add support for icmp(bitcast(icmp_ne(X,Y)),0)...

[X86] MatchVectorAllZeroTest - add support for icmp(bitcast(icmp_ne(X,Y)),0) vector reduction patterns

Many allof/anyof/noneof reduction patterns are canonicalized by bitcasting a vXi1 vector comparison result to iN and compared against 0/-1.

This patch adds support for recognizing a icmp_ne vector comparison against 0, which matches an 'whole vectors are equal' comparison pattern.

There are a few more steps to follow in future patches - we need to add support to MatchVectorAllZeroTest for comparing against -1 (in some cases), and this initial refactoring of LowerVectorAllZero to LowerVectorAllEqual needs to be extended so we can fully merge with the similar combineVectorSizedSetCCEquality code (which deals with scalar integer memcmp patterns).

Another step towards Issue #53419

Differential Revision: https://reviews.llvm.org/D147243