Allow spam as reason for moderating user (#8635)

Author: sigurdm

app/lib/account/models.dart

@@ -79,7 +79,7 @@ class User extends db.ExpandoModel<String> {
       InvalidInputException.checkAnyOf(
         moderatedReason,
         'reason',
-        UserModeratedReason._values,
+        UserModeratedReason.values,
       );
     } else {
       InvalidInputException.checkNull(moderatedReason, 'reason');
@@ -416,13 +416,15 @@ abstract class UserModeratedReason {
   static const bot = 'bot';
   static const illegalContent = 'illegal-content';
   static const policyViolation = 'policy-violation';
+  static const spam = 'spam';
   static const unfoundedNotifications = 'unfounded-notifications';
   static const unfoundedAppeals = 'unfounded-appeals';
 
-  static const _values = {
+  static const values = {
     bot,
     illegalContent,
     policyViolation,
+    spam,
     unfoundedNotifications,
     unfoundedAppeals,
   };

app/lib/admin/actions/moderate_user.dart

@@ -30,7 +30,8 @@ The active web sessions of the user will be expired.
     'case':
         'The ModerationCase.caseId that this action is part of (or `none`).',
     'user': 'The user-id or the email of the user to be moderated',
-    'reason': 'The reason for user moderation.',
+    'reason':
+        'The reason for user moderation. One of ${UserModeratedReason.values.join(', ')}.',
     'state':
         'Set moderated state true / false. Returns current state if omitted.',
     'note': 'Optional note to store (internal).'