DEV: Display better output when inspecting service steps

This patch aims to improve the steps inspector output:
- The service class name is displayed at the top.
- Next to each step is displayed the time it took to run said step.
- Steps that didn’t run are hidden.
- `#inspect` automatically outputs the error when it is present.

plugins/chat/plugin.rb

@@ -450,7 +450,7 @@ after_initialize do
         )
 
       if creator.failure?
-        Rails.logger.warn "[discourse-automation] Chat message failed to send:\n#{creator.inspect_steps.inspect}\n#{creator.inspect_steps.error}"
+        Rails.logger.warn "[discourse-automation] Chat message failed to send:\n#{creator.inspect_steps}"
       end
     end
   end