Add session timeout indicator

[grioux-neo]

Is your feature request related to a problem? Please describe.
There is no indication of how long the session timer is nor how long there is before the session times out.

Describe the solution you'd like
Add a countdown timer that begins with the same number as the server session timer and resets with every action that is counted as activity

Describe alternatives you've considered
Rearchitect the system to provide actual session timeout display

Additional context
Displayed timer doesn't have to be the exact server timer, it just needs to display a countdown