[GlobalIsel][X86] Legalize G_CTPOP and G_CTLZ

G_BSWAP was reverted -> added to this diff.

check plan: ninja check-llvm-codegen-x86

Future work: G_SUB and G_ZEXT need some modernization.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D150677