refactor: repository worker (#14489)

docs/development/local-development.md

lib/config/validation.ts

lib/constants/platform.spec.ts

lib/workers/repository/changelog/index.ts

lib/workers/repository/onboarding/pr/index.ts

lib/workers/repository/process/write.spec.ts

lib/workers/repository/process/write.ts

...epository/update/branch/__snapshots__/commit.spec.ts.snap

...tory/update/branch/__snapshots__/get-updated.spec.ts.snap

lib/workers/repository/update/branch/artifacts.spec.ts

lib/workers/repository/update/branch/artifacts.ts

lib/workers/repository/update/branch/auto-replace.spec.ts

lib/workers/repository/update/branch/auto-replace.ts

lib/workers/repository/update/branch/automerge.spec.ts

lib/workers/repository/update/branch/automerge.ts

lib/workers/repository/update/branch/check-existing.spec.ts

lib/workers/repository/update/branch/check-existing.ts

lib/workers/repository/update/branch/commit.spec.ts

lib/workers/repository/update/branch/commit.ts

...itory/update/branch/execute-post-upgrade-commands.spec.ts