fix(renderer): render into viewport instead of resizing SurfaceView

Avoid SurfaceView relayouts during display resolution and extra keys
toolbar changes by rendering X11 content into a configurable viewport
inside a fullscreen surface.

This reduces flickering, stale frames and visual jumps caused by
SurfaceView geometry updates racing against renderer buffer updates.

Signed-off-by: Twaik Yont <9674930+twaik@users.noreply.github.com>