Add new "short descriptor" algorithm to MARK-V codec.
Add three shader compression models:
lite - fast, poor compression
mid - balanced
max - best compression
- switched from C to C++
- moved MARK-V model creation from backend to frontend
- The same MARK-V model object can be used to encode/decode multiple
files
- Added MARK-V model factory (currently only one option)
- Added --validate option to spirv-markv (run validation while
encoding/decoding)