Fix issue #22013372: Assist should take translationX and friends...

...into account when calculating the position information

Actually what we need here is the full transformation matrix, if it
is available.  And that means actually computing the location of
views on the screen requires doing this all through transformations,
so the AssistVisualizer has been changed to do this (while still
also keeping the old mechanism for comparison to verify that things
are working correctly).

Also added new properties for elevation and alpha.

And optimized the parcelling of AssistStructure to not write things
that aren't needed; this reduces the parcelled size by about half.

Change-Id: I50b0dd2e6599c74701a5d188617a3eff64b07d03