Persist TestrunMessages and store timestamp

So far, the Testrun messages are in addition to the Tesstrun.output column

app/controllers/execution_environments_controller.rb

@@ -30,7 +30,7 @@ class ExecutionEnvironmentsController < ApplicationController
   def execute_command
     runner = Runner.for(current_user, @execution_environment)
     output = runner.execute_command(params[:command], raise_exception: false)
-    render json: output
+    render json: output.except(:messages)
   end
 
   def working_time_query