Show an overlay with a spinner when slow gUM is fired

* Listens for suspend events from jitsi-power-monitor on postis channel.

* Removes duplicated type and actions.

* Moves suspendDetected state from overlay to power-monitor feature.

* fix(connection): reload immediately on possible split-brain

There isn't an explicit way to know when a split brain
scenario has happened. It is assumed it arises when an
"item-not-found" connection error is encountered early
on in the conference. So, store when a connection has
happened so it be calculated how much time has
elapsed and if the threshold has not been exceeded
then do an immediate reload of the app instead of
showing the overlay with a reload timer.

* squash: rename isItemNotFoundError -> isShardChangedError

Adds a fatal error state on which will depend whether or not the reload
screen is to be displayed. It is to happen when a relevant fatal error
action is not claimed by any feature for error recovery (the recoverable
flag is not set).