ci: migrate long sims (#6084)

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.

Makefile

@@ -8,6 +8,8 @@ LEDGER_ENABLED ?= true
 BINDIR ?= $(GOPATH)/bin
 SIMAPP = ./simapp
 MOCKS_DIR = $(CURDIR)/tests/mocks
+HTTPS_GIT := https://github.com/cosmos/cosmos-sdk.git
+DOCKER_BUF := docker run -v $(shell pwd):/workspace --workdir /workspace bufbuild/buf
 
 export GO111MODULE = on
 
@@ -255,6 +257,14 @@ proto-lint:
 proto-check-breaking:
 	@buf check breaking --against-input '.git#branch=master'
 
+proto-lint-docker:
+	@$(DOCKER_BUF) check lint --error-format=json
+.PHONY: proto-lint
+
+proto-check-breaking-docker:
+	@$(DOCKER_BUF) check breaking --against-input $(HTTPS_GIT)#branch=master
+.PHONY: proto-check-breaking-ci
+
 TM_URL           = https://raw.githubusercontent.com/tendermint/tendermint/v0.33.1
 GOGO_PROTO_URL   = https://raw.githubusercontent.com/regen-network/protobuf/cosmos
 COSMOS_PROTO_URL = https://raw.githubusercontent.com/regen-network/cosmos-proto/master