FIX: supports groups field in post_created_edited (#28773)

To achieve this this commit does the following:
- create a new `groups field, ideally we would have reused the existing group field, but many automations now have the expectation that this field will return a group id and not an array of group ids, which makes it a dangerous change
- alter the code in `post_created_edited` to use this new groups field and change the logic to use an array
- migrate the existing group fields post_created_edited automations to change name from `restricted_group` to `restricted_groups`, the component from `group` to `groups` and the metadata from `{"value": integer}` to `{"value": [integer]}`

plugins/automation/lib/discourse_automation/triggers/post_created_edited.rb

@@ -14,7 +14,7 @@ DiscourseAutomation::Triggerable.add(DiscourseAutomation::Triggers::POST_CREATED
         }
   field :restricted_category, component: :category
   field :restricted_tags, component: :tags
-  field :restricted_group, component: :group
+  field :restricted_groups, component: :groups
   field :ignore_automated, component: :boolean
   field :ignore_group_members, component: :boolean
   field :valid_trust_levels, component: :"trust-levels"