feat(docker): preserve registry in depName (#3133)

lib/datasource/docker/index.js

lib/manager/ansible/extract.js

lib/manager/bundler/artifacts.js

lib/manager/circleci/extract.js

lib/manager/docker-compose/extract.js

lib/manager/dockerfile/extract.js

lib/manager/dockerfile/update.js

lib/manager/kubernetes/extract.js

test/datasource/__snapshots__/docker.spec.js.snap

test/datasource/docker.spec.js

test/manager/ansible/__snapshots__/extract.spec.js.snap

test/manager/circleci/__snapshots__/extract.spec.js.snap

...manager/docker-compose/__snapshots__/extract.spec.js.snap

test/manager/docker-compose/update.spec.js

test/manager/dockerfile/__snapshots__/extract.spec.js.snap

test/manager/dockerfile/extract.spec.js

test/manager/dockerfile/update.spec.js

test/manager/gitlabci/__snapshots__/extract.spec.js.snap

test/manager/kubernetes/__snapshots__/extract.spec.js.snap

test/manager/kubernetes/update.spec.js