Idle Modal: Basic Implementation

[richard-cox]

Parent Issue: #7776

Dependent Issue: #8317

• Create a modal as per design - UI inactivity notification and timeout settings: Design #8317
• Implement the functionality as described in the description WITHOUT configurable options
  • This will default to be off
  • The amount of idle time before the modal is shown can be hardcoded

[edenhernandez-suse]

Final design and specs in the Specs Confluence page