Nav bar: fix tablet density change issues

 - Re-inflate the contents of the NavigationBarInflaterView
 - Call up to parent to notify the contents has been reinflated
 - Fix how default tunable is handled, so that the resource is
   reloaded on density change

Change-Id: If25f68d01eedd3319b0c270e1cf80ac382eea637
Fixes: 27227522