Backend changes for new UI

[a-martynovich]

• On every page there needs to be "Current Trust Score" and "Actions Solved"
• "Actions Solved" is how many RAs were solved since his week's Monday
• Implement new Welcome/Dashboard view #591 - need last week's average of average trust score
• Implement new Welcome/Dashboard view #591 - need short RA texts written out in subtasks of Write out FAQ entries for recommended actions wott-io#198
• Implement new CVE view #596 - need a count of high, med and low CVEs and a max of high, med, low CVEs since Monday (need additional history element for this) and since last week's Monday
• Automatically reload nodes table on event. #615 - an endpoint to check node list length periodically. Could be made using an already existing endpoint with HEAD request.
  * Implement new Welcome/Dashboard view #591, 594 - solved RAs should appear too - TBD
  * Implement new Welcome/Dashboard view #591 - need dummy RA list for the "Welcome" state (when Node List is empty) - just use placeholders

[a-martynovich]

done