FEATURE: Implement SiteSetting to Allow Anonymous Likes (#22131)

Allow anonymous users (logged-in, but set to anonymous posting) to like posts

---------

Co-authored-by: Emmett Ling <eling@zendesk.com>
Co-authored-by: Nat <natalie.tay@discourse.org>

lib/guardian.rb

@@ -620,10 +620,14 @@ class Guardian
   private
 
   def is_my_own?(obj)
-    unless anonymous?
-      return obj.user_id == @user.id if obj.respond_to?(:user_id) && obj.user_id && @user.id
-      return obj.user == @user if obj.respond_to?(:user)
+    if anonymous?
+      return(
+        SiteSetting.allow_anonymous_likes? && obj.class == PostAction && obj.is_like? &&
+          obj.user_id == @user.id
+      )
     end
+    return obj.user_id == @user.id if obj.respond_to?(:user_id) && obj.user_id && @user.id
+    return obj.user == @user if obj.respond_to?(:user)
 
     false
   end

lib/guardian/post_guardian.rb

@@ -43,7 +43,10 @@ module PostGuardian
     already_did_flagging = taken.any? && (taken & PostActionType.notify_flag_types.values).any?
 
     result =
-      if authenticated? && post && !@user.anonymous?
+      if authenticated? && post
+        # Allow anonymous users to like if feature is enabled and short-circuit otherwise
+        return SiteSetting.allow_anonymous_likes? && (action_key == :like) if @user.anonymous?
+
         # Silenced users can't flag
         return false if is_flag && @user.silenced?