Merge pull request #8658 from metabase/column-and-table-comments

src/metabase/driver/generic_sql.clj

src/metabase/sync/interface.clj

src/metabase/sync/sync_metadata/fields.clj

src/metabase/sync/sync_metadata/tables.clj

test/metabase/driver/generic_sql_test.clj

test/metabase/driver/postgres_test.clj

test/metabase/sync/sync_metadata/comments_test.clj

test/metabase/test/data/generic_sql.clj

test/metabase/test/data/h2.clj

test/metabase/test/data/interface.clj

test/metabase/test/data/postgres.clj