Fix Magnifier position updates

When the magnifier content moves relative to the parent surface,
it will call setPosition on the content surface control. This conflicts
with position updates called by the BlastBufferQueue adapter
causing a flicker on screen. Fix this by providing a wrapper surface
to BlastBufferQueue adapater to send buffer updates.

Fixes: 186072574
Test: Select text and see magnifier surface does not flicker or move
around

Change-Id: Idfcc06a5d90f400f69e5cbe91008a0cb59fd4646