DEV: Add post_action_users_list modifier for PostActionUsersController (#25740)

This commit adds another plugin modifier related to post
actions, similar to ae24e04a5ed1921908c8cf1926245fed40aee562.

This will be used to exclude users who liked _and_ reacted to
the post, since now in discourse-reactions we make a Like when
a user reacts too. This will affect the display of the post footer.

app/controllers/post_action_users_controller.rb

@@ -12,19 +12,9 @@ class PostActionUsersController < ApplicationController
     page_size = fetch_limit_from_params(default: INDEX_LIMIT, max: INDEX_LIMIT)
 
     # Find the post, and then determine if they can see the post (if deleted)
-    post = Post.with_deleted.where(id: params[:id].to_i).first
+    post = Post.with_deleted.find_by(id: params[:id].to_i)
     guardian.ensure_can_see!(post)
 
-    unknown_user_ids = Set.new
-    if current_user.present?
-      result = DB.query_single(<<~SQL, user_id: current_user.id)
-        SELECT mu.muted_user_id AS id FROM muted_users AS mu WHERE mu.user_id = :user_id
-        UNION
-        SELECT iu.ignored_user_id AS id FROM ignored_users AS iu WHERE iu.user_id = :user_id
-      SQL
-      unknown_user_ids.merge(result)
-    end
-
     post_actions =
       post
         .post_actions
@@ -34,20 +24,23 @@ class PostActionUsersController < ApplicationController
         .order("post_actions.created_at ASC")
         .limit(page_size)
 
+    post_actions =
+      DiscoursePluginRegistry.apply_modifier(:post_action_users_list, post_actions, post)
+
     if !guardian.can_see_post_actors?(post.topic, post_action_type_id)
-      raise Discourse::InvalidAccess unless current_user
+      raise Discourse::InvalidAccess if current_user.blank?
       post_actions = post_actions.where(user_id: current_user.id)
     end
 
     action_type = PostActionType.types.key(post_action_type_id)
     total_count = post["#{action_type}_count"].to_i
-
+    post_actions = post_actions.to_a
     data = {
       post_action_users:
         serialize_data(
-          post_actions.to_a,
+          post_actions,
           PostActionUserSerializer,
-          unknown_user_ids: unknown_user_ids,
+          unknown_user_ids: current_user_muting_or_ignoring_users(post_actions.map(&:user_id)),
         ),
     }
 
@@ -55,4 +48,14 @@ class PostActionUsersController < ApplicationController
 
     render_json_dump(data)
   end
+
+  private
+
+  def current_user_muting_or_ignoring_users(user_ids)
+    return [] if current_user.blank?
+    UserCommScreener.new(
+      acting_user: current_user,
+      target_user_ids: user_ids,
+    ).actor_preventing_communication
+  end
 end