[AMDGPU][GlobalIsel] Replace wip_match_opcode with MIR patterns with basic match and apply clauses. (#219185)
This patch replaces wip_match_opcode mechanism with MIR-pattern matching
for opcodes with no or partial possibility for declarative pattern
match/apply clause for the AMDGPU-specifc GICombines.
The following opcodes are covered : `G_TRUNC`, `G_AMDGPU_FMED3`,
`G_FCANONICALIZE`, `G_FNEG`, `G_MUL` and `G_SEXT_INREG`.