Improved Summary dashboard for Security Threat Tool 'Failed Checks'

We need to improve (create a new one) panel  to be able to: 

• Display number of currently failed checks in the system if the STT is enabled 
  • 0 (green) if the total checks == 0
  • otherwise 2 / 0 / 1 (red, orange, blue) if total checks > 0
• Display a customizable text message if STT is disabled
  • make it possible to edit the text message via a property in Panel options
  • display the following message "Security Threat Tool is disabled. Check PMM Settings"

NB: Won't do -> `make it possible to edit the text message via a property in Panel options`, because we need a link to another panel, and currently the config panel allows to pass only strings, not HTML