fix: map materialized views to views when granting permissions

Author: newtonapple

sqlmesh/core/engine_adapter/bigquery.py

@@ -1377,7 +1377,7 @@ def _get_grant_expression(self, table: exp.Table) -> exp.Expression:
 
     @staticmethod
     def _grant_object_kind(table_type: DataObjectType) -> str:
-        if table_type == DataObjectType.VIEW:
+        if table_type == DataObjectType.VIEW or table_type == DataObjectType.MATERIALIZED_VIEW:
             return "VIEW"
         return "TABLE"