[AMDGPU] gfx11 VOPC instructions

Supports encoding existing instrutions on gfx11 and MC support for the new VOPC
dpp instructions.

Patch 19/N for upstreaming of AMDGPU gfx11 architecture

Depends on D126978

Reviewed By: rampitec, #amdgpu

Differential Revision: https://reviews.llvm.org/D126989