Show success message on MR approval settings save

This commit adds a flash message on top of the page when MR approval
settings have been updated successfully.

ee/app/assets/javascripts/approvals/stores/modules/group_settings/actions.js

@@ -34,6 +34,10 @@ export const updateSettings = ({ commit, state }, endpoint) => {
     .put(endpoint, payload)
     .then(({ data }) => {
       commit(types.UPDATE_SETTINGS_SUCCESS, data);
+      createFlash({
+        message: __('Merge request approval settings have been updated.'),
+        type: 'notice',
+      });
     })
     .catch(({ response }) => {
       const error = response?.data?.message;

ee/spec/frontend/approvals/stores/modules/group_settings/actions_spec.js

@@ -92,7 +92,12 @@ describe('EE approvals group settings module actions', () => {
             { type: types.UPDATE_SETTINGS_SUCCESS, payload: data },
           ],
           [],
-        );
+        ).then(() => {
+          expect(createFlash).toHaveBeenCalledWith({
+            message: 'Merge request approval settings have been updated.',
+            type: 'notice',
+          });
+        });
       });
     });
 

locale/gitlab.pot

@@ -18533,6 +18533,9 @@ msgstr ""
 msgid "Merge request (MR) approvals"
 msgstr ""
 
+msgid "Merge request approval settings have been updated."
+msgstr ""
+
 msgid "Merge request approvals"
 msgstr ""