Move full delete logic into ActionHandler.

Was spread across DirectoryFragment and UserInputHandlers.
Drop "android" test package in favor of the generic "testing".
Add an interface for ActionModeController (ActionModeAddons), so can be tested.
Moved ActionModeHandler out of dirlist ../up d dir.

Change-Id: Id915519656f163d3c413fe5d440d866c3ce4e2ca