Add 'none' for moderate action 'case' parameter documentation. (#8071)

Author: isoos

app/lib/admin/actions/moderate_package.dart

@@ -22,7 +22,8 @@ Note: the action may take a longer time to complete as the public archive bucket
       archive files will be copied over from the (private) canonical archive bucket.
 ''',
   options: {
-    'case': 'The ModerationCase.caseId that this action is part of.',
+    'case':
+        'The ModerationCase.caseId that this action is part of (or `none`).',
     'package': 'The package name to be moderated',
     'state':
         'Set moderated state true / false. Returns current state if omitted.',

app/lib/admin/actions/moderate_package_versions.dart

@@ -26,7 +26,8 @@ final moderatePackageVersion = AdminAction(
 Set the moderated flag on a package version (updating the flag and the timestamp).
 ''',
   options: {
-    'case': 'The ModerationCase.caseId that this action is part of.',
+    'case':
+        'The ModerationCase.caseId that this action is part of (or `none`).',
     'package': 'The package name to be moderated',
     'version': 'The version to be moderated',
     'state':

app/lib/admin/actions/moderate_publisher.dart

@@ -20,7 +20,8 @@ moderated package page says it is moderated, packages owned by publisher
 can't be updated, administrators must not be able to update publisher options.
 ''',
   options: {
-    'case': 'The ModerationCase.caseId that this action is part of.',
+    'case':
+        'The ModerationCase.caseId that this action is part of (or `none`).',
     'publisher': 'The publisherId to be moderated',
     'state':
         'Set moderated state true / false. Returns current state if omitted.',

app/lib/admin/actions/moderate_user.dart

@@ -28,7 +28,8 @@ and actions that they may be able to do will be blocked because of that.
 The active web sessions of the user will be expired.
 ''',
   options: {
-    'case': 'The ModerationCase.caseId that this action is part of.',
+    '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.',
     'state':