Fix custom sms gateway cannot be disabled because no save button

ref DEV-2513

Author: louischan-oursky

portal/src/graphql/portal/SMSProviderConfigurationScreen.tsx

@@ -1005,7 +1005,11 @@ function SMSProviderConfigurationContent(props: {
               )}
             </div>
           </>
-        ) : null}
+        ) : (
+          <div className={styles.widget}>
+            <FormSaveButton />
+          </div>
+        )}
       </ScreenContent>
       <ReauthDialog
         isHidden={isReauthDialogHidden}