[AArch64] Use known zero bits when creating BIC

If we know bits are already 0, we will not need to clear them again with a BIC.
So we can use KnownBits to shrink the size of the constant in the creation BIC
from And, potentially undoing the known-bits folds that happen during
compilation.

BIC only has a single register operand for input and output, so has less
scheduling freedom than a AND, but usually saves the materialization of a
constant.

Differential Revision: https://reviews.llvm.org/D154217