Cancel ci if no .go files have been touched. There is no clean way of
doing this so i opted to `exit 1` on the diff job if no go files were
changed and have builds depend on diff passing
- migrate proto checks to github actions.
- providing make commands to use buf within docker.
- test-sim-multi-seed-long migration to github actions. Follows same
logic and only runs on release branches.
- add protobuf section to CONTRIBUTING.md.
dependabot[bot]
Marko