Summary of changes:
- Consolidate VOP tests by encoding. Currently, some files include tests for many encodings.
- Separate VOP1/VOP2/VOPC tests. Some of these need additional corrections because they use 16-bit VGPRs they cannot really address.
- Separate tests for v_cmp_ and v_cmpx_ opcodes.
- Remove identical tests (found more than 1000).