refactor: consolidate duplicate interface files to interfaces package

- Move 36 duplicate interface files from contracts and token-distribution
  to interfaces package
- Update all import statements across contracts, token-distribution,
  horizon, and subgraph-service to use @graphprotocol/interfaces
- Delete duplicate interface files from source packages
- Fix pragma versions for compatibility across compiler configurations
- Add @graphprotocol/interfaces dependency to token-distribution

All builds and tests passing.

Author: RembrandtK