FIX: Add missing user_id args for ChatMessage.cook (#19508)

In both ChatMessage#rebake! and in ChatMessageProcessor
when we were calling ChatMessage.cook we were missing the
user_id to cook with, which causes missed hashtag cooks
because of missing permissions.

plugins/chat/spec/lib/chat_message_processor_spec.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+RSpec.describe Chat::ChatMessageProcessor do
+  fab!(:message) { Fabricate(:chat_message) }
+
+  it "cooks using the last_editor_id of the message" do
+    ChatMessage.expects(:cook).with(message.message, user_id: message.last_editor_id)
+    described_class.new(message)
+  end
+end