Themes: Pass resource IDs instead of bitmaps [1/2]

Rather than passing around bitmaps in the ComposedIconInfo we
can pass the resource IDs associated with each of the components
and retrieve those drawables when composing the icon.

Change-Id: If855e60e505571f25316e6728e423fbee62c32d3
Merge "Themes: Pass resource IDs instead of bitmaps [1/2]" into kk44