Stop trying to draw a view not attached to the view tree

The behavior of the framework when we try to do so is undefined. In our
case, it almost work, but no clipping is applied, which is a problem for
Android S (before that, widget couldn't use clipping in the first
place).

Instead of drawing the view through a drawable, this really add the view
and adds also a badge ImageView for badges instead of drawing them
indirectly.

Note that, temporarily, we have to re-allow drawing the view after it
has been attached, but the underlying framework bug being fixed, this
should be fine (I tested it and it really seems to be).

Bug: 183609936
Test: Using hand designed app (see bug)
Change-Id: I929ef8fc81c98c49406f2d940cd5efc28319886d