Cleaned ShellListView_Navigated

I removed [async] and all [Task.Run] from the method.

From: Aaron Campf
Subject: Describing reasons for changing code

After testing and research I have concluded that neither [async] or the
[Task.Run] had any actually effect
[Dispatcher.BeginInvoke] is still called and that is the only way to
edit the UI without already being on the UI Thread

[async] is only usefull when you want the method to use threads but not
freeze the current thread while the new thread does its work
Because [async] had no real effect, the only thing that matters is
[Task.Run]

[Task.Run] Do nothing but create a [Dispatcher.BeginInvoke] which is the
same as if we removed the [Task.Run] and created them directly
Merge branch 'BetterExplorer2.5' of https://github.com/DimitarCC/BetterExplorer into BetterExplorer2.5

Conflicts:
	Shell/ShellViewEx.cs