Add maintenance banner on UI (#797)

* fix bug on email separator

Signed-off-by: Denis barbaron <denis.barbaron@orange.com>

* allow group name change

Signed-off-by: Denis barbaron <denis.barbaron@orange.com>

* add maintenance banner on UI

Signed-off-by: Denis barbaron <denis.barbaron@orange.com>

* removes unnecessary comments

Signed-off-by: Denis barbaron <denis.barbaron@orange.com>

---------

Signed-off-by: Denis barbaron <denis.barbaron@orange.com>

res/app/settings/general/alert-message/alert-message-controller.js

@@ -0,0 +1,41 @@
+/**
+* Copyright © 2024 code initially contributed by Orange SA, authors: Denis Barbaron - Licensed under the Apache license 2.0
+**/
+
+module.exports = function AlertMessageCtrl(
+  $scope
+, SettingsService
+) {
+
+  $scope.defaultAlertMessage = {
+    data: '*** This site is currently under maintenance, please wait ***'
+  , activation: 'False'
+  , level: 'Critical'
+  }
+
+  SettingsService.bind($scope, {
+    target: 'alertMessage'
+  , source: 'alertMessage'
+  , defaultValue: $scope.defaultAlertMessage
+  })
+
+  $scope.alertMessageActivationOptions = ['True', 'False']
+  $scope.alertMessageLevelOptions = ['Information', 'Warning', 'Critical']
+
+  $scope.$watch(
+    function() {
+      return SettingsService.get('alertMessage')
+    }
+  , function(newvalue) {
+      if (typeof newvalue === 'undefined') {
+        SettingsService.set('alertMessage', $scope.defaultAlertMessage)
+      }
+    }
+  )
+
+  $scope.$on('user.menu.users.updated', function(event, message) {
+    if (message.user.privilege === 'admin') {
+      $scope.alertMessage = message.user.settings.alertMessage
+    }
+  })
+}