refactor: renovateRepository split (#1928)

lib/workers/repository/index.js

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

lib/workers/repository/onboarding/pr/pr-list.js

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

lib/workers/repository/process/index.js

lib/workers/repository/process/write.js

lib/workers/repository/updates/generate.js

test/workers/repository/__snapshots__/index.spec.js.snap

test/workers/repository/index.spec.js

...tory/onboarding/pr/__snapshots__/base-branch.spec.js.snap

...pository/onboarding/pr/__snapshots__/pr-list.spec.js.snap

test/workers/repository/onboarding/pr/base-branch.spec.js

test/workers/repository/onboarding/pr/index.spec.js

test/workers/repository/onboarding/pr/pr-list.spec.js

...rkers/repository/process/__snapshots__/index.spec.js.snap

...orkers/repository/process/__snapshots__/sort.spec.js.snap

test/workers/repository/process/extract-update.spec.js

test/workers/repository/process/index.spec.js

test/workers/repository/process/sort.spec.js

test/workers/repository/process/write.spec.js