Merge pull request #3915 from metabase/support-named-aggregations

src/metabase/driver/druid/query_processor.clj

src/metabase/driver/generic_sql/query_processor.clj

src/metabase/query_processor/annotate.clj

src/metabase/query_processor/expand.clj

src/metabase/query_processor/interface.clj

src/metabase/query_processor/macros.clj

test/metabase/api/dataset_test.clj

test/metabase/driver/druid_test.clj

test/metabase/events/activity_feed_test.clj

test/metabase/query_processor/expand_resolve_test.clj

test/metabase/query_processor/macros_test.clj

test/metabase/query_processor_test.clj

...ase/query_processor_test/expression_aggregations_test.clj

test/metabase/test/data.clj

test/metabase/test/util.clj