Rework GET /api/collection/:id to return things in 'search-friendly' format

src/metabase/api/card.clj

src/metabase/api/collection.clj

src/metabase/models/collection.clj

test/metabase/api/collection_test.clj

test/metabase/models/collection_test.clj

.../metabase/query_processor/middleware/permissions_test.clj

test/metabase/test/data/users.clj