[Target][ARM] Fold or(A, B) more aggressively for I1 vectors

This patch makes the folding of or(A, B) into not(and(not(A), not(B)))
more agressive for I1 vector. This only affects Thumb2 MVE and improves
codegen, because it removes a lot of msr/mrs instructions on VPR.P0.

This patch also adds a xor(vcmp) -> !vcmp fold for MVE.

Differential Revision: https://reviews.llvm.org/D77202