Updating the ui for widget restore flow

> Pending widget show a PreloadIconDrawable to indicate
installation progress
> Only the concerned widgets are reinflated on package
install and not the whole workspace.
> Adding support for storing default package icon in
IconCache

issue: 10779035
issue: 16737660

Change-Id: Id787ae4a5ef72d6e01aeb5a1bae5ab8840037679