Split up /api/collection/:id endpoint and cleanup collections FE

frontend/src/metabase/admin/permissions/selectors.js

frontend/src/metabase/components/CollectionLanding.jsx

frontend/src/metabase/containers/CollectionPicker.jsx

frontend/src/metabase/containers/Overworld.jsx

frontend/src/metabase/entities/collections.js

...d/src/metabase/entities/containers/EntityObjectLoader.jsx

frontend/src/metabase/entities/dashboards.js

frontend/src/metabase/entities/pulses.js

frontend/src/metabase/entities/questions.js

frontend/src/metabase/entities/search.js

frontend/src/metabase/home/containers/ArchiveApp.jsx

frontend/src/metabase/home/containers/SearchApp.jsx

frontend/src/metabase/schema.js

src/metabase/api/collection.clj

test/metabase/api/collection_test.clj