Removing interrupt on shutdown as a test
Additional fixes to stop HTTP get operations a bit faster. This may result in error messages at the app level during shutdown.
The goal is to more (more) sure that all shutdown tasks execute before the app closes
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Changed SHUTDOWN priorty tasks to set EXECUTE_NORMALLY_ON_SHUTDOWN parameter to avoid a possible race during shutdown that would have resulted in SHUTDOWN tasks being removed from the queue

Increased the timeout from 1sec to 15sec if the user side-swipe-exits. During that period, the app will hold the calling thread and not release it until it has finished what it needs to finish.

Removed some dead code loops that were iterating over tasks during shutdown but doing nothing
Don't hold for dedicated threads to complete during shutdown
Added SHUTDOWN_UI task priority which is queued to UI thread at the beginning of app shutdown.
HttpGetter is taken to run like a hidden thread, replaced with a new Worker if running during shutdown. Thus the associated thread close and network resources can be collected by the platform as the VM is cleaned up, but we do not delay close based on network get.
Added missing Task priority string causing exceptions on logging.
Initial changes before shift to "thread which calls shutdown() assumes responsibility for finishing everything"
Many changes to simplify shutdown down to a single thread
Running tests on phone. App does not complete close. Added debug lines.
Shutdown removed and streamlined dead code. Removed shutdown state. Added volatile for shutdownComplete