Add alert prompting user when no test files are found

[marksands]

If no test files are found, the an alert should prompt the user informing them that no test files were found. The alert should automatically be hidden/fade out after a delay, maybe 1 second, whatever feels natural.

I'm thinking a menu of options that give the user the option to create and add the new test file in the default Tests group would be a cool feature to have.