Fix some oddities in ResolverActivity

* Fix layout for small-screen devices in landscape.

* Properly re-enable buttons after restoring instance state.

* Scroll to the currently selected item after restoring instance
  state.

* Smooth scroll to the currently selected item if the user changes
  selection to an item slightly out of view.

* Place grid scroll bar outside the grid's padding.

* Make the current text read a bit more naturally.

Bug 6460135

Change-Id: Ic60330365cdd815e7517f01b36bcdc9d1c857f30