* Simplified task control by having all logic in a single class and using async control mechanism
* Fixed the tests
* Made the marking of a backup partial explicitly communicated if the enumeration process is stopped.
* Added support for pausing active transfers
* Introduced transfer token to abort operations.
* Updated the way LiveControl is emitting events.
* Retains the paused state of the server across reboots, this fixes#5760.
* Reworked the way throttle speeds are propagated through LiveControls.
* Added option to pause transfers in the UI.
* Removed throttle settings from the LiveControls class so it is exclusively handled by the ApplicationSettings.
* Removed `thread-priority` as it does not work at all when tasks are used.
* Fixed the stop dialog and API to only support stop and abort.
* Removed unused variables
Kept the infrastructure to allow re-introducing it later if a better source for a device key is found.
Added support for not having any valid settings encryption key.
Added warnings if the user is running without a settings encryption key.
Added additional checks during startup to help with troubleshooting and configuring a setup with a settings encryption key.
Docker builds will now warn if no encryption key is set.
This fixes#5518
