The KTEST instruction sets the C flag if the result of anding both operands together is all 1s. We can use this to lower (icmp eq/ne (bitcast (vXi1 X), -1)
Use KORTEST instead of KTEST since it has the correct flag behavior. Use KORTEST for all 0s check too. Enable usage of KORTEST on AVX512F for v16i1. KTEST v16i1 was added with AVX512DQ but AVX512F had KTEST.