feat(worker): convert parts to typescript (#4388)

lib/datasource/common.ts

lib/types/clean-git-ref.d.ts

lib/workers/repository/process/extract-update.js

lib/workers/repository/process/lookup/common.ts

lib/workers/repository/process/lookup/filter.ts

lib/workers/repository/process/lookup/index.ts

lib/workers/repository/process/lookup/rollback.ts

lib/workers/repository/updates/branchify.ts

lib/workers/repository/updates/flatten.ts

lib/workers/repository/updates/generate.ts

test/workers/repository/updates/branchify.spec.js