[database] new, API table metadata (#9002)

Migrates and completely removes: '/superset/table/<database_id>/<table_name>/<schema>/'
- Guarantees database filtering based on the user permissions
- Full OpenAPI spec
- Better error handling

tests/core_tests.py

@@ -554,13 +554,6 @@ class CoreTests(SupersetTestCase):
         data = self.run_sql(sql, "fdaklj3ws")
         self.assertEqual(data["data"][0]["test"], "2017-01-01T00:00:00")
 
-    def test_table_metadata(self):
-        maindb = utils.get_example_database()
-        data = self.get_json_resp(f"/superset/table/{maindb.id}/birth_names/null/")
-        self.assertEqual(data["name"], "birth_names")
-        assert len(data["columns"]) > 5
-        assert data.get("selectStar").startswith("SELECT")
-
     def test_fetch_datasource_metadata(self):
         self.login(username="admin")
         url = "/superset/fetch_datasource_metadata?" "datasourceKey=1__table"