fix(core): deprecated stale protos and add better upgrade comments (#2793)

### Proposed Changes

* Deprecated `selectors` that have drifted from original implementation
and have not been implemented
* Improve legacy kas grants deprecation upgrade comments

### Checklist

- [ ] I have added or updated unit tests
- [ ] I have added or updated integration tests (if appropriate)
- [ ] I have added or updated documentation

### Testing Instructions

Author: jakedoublev