Show persistent message on idle time out

As a user, it'd be nice to have a persistent message when I come back to a session and am logged out.

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Two times today, I've been idling on NX3 and on return to the screen have had a pause then realized I am logged out presumably due to idling. One benefit of NEXUS-7755 was that there was a history including that you were logged out. Right now, you can potentially just click anonymously before realizing what happened. Suggesting a message on the screen relaying you have been logged out that persists until the user clicks it off (or otherwise notes it as being seen). If NEXUS-7755 or like history is restored, then this could likely be OBE.

Acceptance Criteria:

• When a user is logged out due to timeout, show the user a dialog that indicates to them they have been logged out