fix: change database save in DatasourceEditor (#9255)

* fix: change database save in DatasourceEditor

This addresses the issue where pointing a datasource to another database
in the datasource editor is not reflected.

Also addresses:
- a minorcosmetic issue in the datasource editor.
- user/owners list not getting populated

* tests

superset/security/manager.py

@@ -83,6 +83,7 @@ PermissionModelView.list_widget = SupersetSecurityListWidget
 # Limiting routes on FAB model views
 UserModelView.include_route_methods = RouteMethod.CRUD_SET | {
     RouteMethod.ACTION,
+    RouteMethod.API_READ,
     RouteMethod.ACTION_POST,
     "userinfo",
 }