[api] add a timestamp in front of the log message

(at least while I'm hunting slow routes :)

src/api/config/initializers/logging.rb

@@ -25,7 +25,16 @@ def log_process_action(payload)
   end
 end
 
+module TimestampFormatter
+  def call(severity, timestamp, progname, msg)
+    Thread.current[:timestamp_formatter_timestamp] ||= Time.now
+    tdiff = sprintf("%02.2f", Time.now - Thread.current[:timestamp_formatter_timestamp])
+    super(severity, timestamp, progname, "[#{tdiff}] #{msg}")
+  end
+end
+
 ActiveSupport.on_load(:action_controller) do
   include APIInstrumentation::ControllerRuntime
+  Rails.logger.formatter.extend(TimestampFormatter)
 end