FEATURE: Display the Watched Words that caused a post to be flagged. (#31435)

When a post is flagged due to matching watched words, it can be difficult to know what you're looking for, particularly if you have a lot of watched words built up over a long period of time.

This change stores the list of matched words, and later displays them in the review queue, listing which Watched Words were responsible for the flag. Because watched words can change, this is recorded at the time the post is flagged. For posts that were flagged prior to this feature landing, it tries to guess the relevant words based on the current Watched Words set.

lib/post_action_creator.rb

@@ -14,7 +14,8 @@ class PostActionCreator
       message: nil,
       created_at: nil,
       reason: nil,
-      silent: false
+      silent: false,
+      context: nil
     )
       new(
         created_by,
@@ -24,6 +25,7 @@ class PostActionCreator
         created_at: created_at,
         reason: reason,
         silent: silent,
+        context: context,
       ).perform
     end
 
@@ -50,7 +52,8 @@ class PostActionCreator
     created_at: nil,
     queue_for_review: false,
     reason: nil,
-    silent: false
+    silent: false,
+    context: nil
   )
     @created_by = created_by
     @created_at = created_at || Time.zone.now
@@ -73,6 +76,8 @@ class PostActionCreator
     @reason = "queued_by_staff" if reason.nil? && @queue_for_review
 
     @silent = silent
+
+    @context = context
   end
 
   def post_can_act?
@@ -403,6 +408,7 @@ class PostActionCreator
         meta_topic_id: @meta_post&.topic_id,
         reason: @reason,
         force_review: trusted_spam_flagger?,
+        context: @context,
       )
   end