FEATURE: enhance post created edited trigger in automation (#31900)

1. **Multiselect Support for Choice Fields**
   - Added a `multiselect` option to the choices field component
   - Updated Field model to accept arrays as values for choices fields

2. **Post Content Feature Filtering**
   - Added ability to filter posts based on content features:
     - Posts with images
     - Posts with links
     - Posts with code blocks
     - Posts with uploads

3. **Improved Group Filtering**
- Renamed `restricted_user_group` to `restricted_groups` to allow
filtering by multiple groups
- Added `excluded_groups` to replace `ignore_group_members` which was
complex for end users
- Renamed `restricted_groups` to `restricted_inbox_groups` for more
specific PM filtering and clarity.

4. **Public Topics Filter**
- Added a "Public Topics" filter option that excludes all secure
categories

plugins/automation/app/models/discourse_automation/field.rb

@@ -94,7 +94,7 @@ module DiscourseAutomation
       },
       "choices" => {
         "value" => {
-          "type" => %w[string integer null],
+          "type" => %w[string integer null array],
         },
       },
       "tags" => {