Set breadcrumb to Root image when name missing

...istry/explorer/components/details_page/details_header.vue

...registry/explorer/components/list_page/image_list_row.vue

app/assets/javascripts/registry/explorer/constants/common.js

...assets/javascripts/registry/explorer/constants/details.js

app/assets/javascripts/registry/explorer/constants/index.js

app/assets/javascripts/registry/explorer/pages/details.vue

...320901-container-page-says-image-repository-not-found.yml

locale/gitlab.pot

spec/features/groups/container_registry_spec.rb

spec/features/projects/container_registry_spec.rb

...y/explorer/components/details_page/details_header_spec.js

...stry/explorer/components/list_page/image_list_row_spec.js

spec/frontend/registry/explorer/pages/details_spec.js