This PR changes the termination signal to a `CancellationToken` instead of a `ManualResetEvent` as the former works better with async code.
With this change there is no longer a thread being captured during each long poll operation.
This fixes#6452
This removes the WorkerThread class and many of the complications around it.
Instead of having a generic worker, there is now the `QueueRunnerService` which takes on all the resposibilities for handling queued tasks.
This is one step towards removing `FIXMEGlobal`
* Fixed nullability warnings in `Utility.cs`
* Fixed a number of nullability issues and warnings
* More nullable fixes
* Fixed the overwrite issue
* Fixed additional nullability issues
* Removed additional nullability issues
* More nullability fixes and added some xmldoc
* Added more xmldocs and removed an unused argument
* Removed more warnings
* 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
Kenneth Skovhede