Request embedded focus if a SurfacePackage was added to SV

If the SV was already focus when a SurfacePackage is attached, it should
request focus to the embedded. This allows focus to work better for the
developer perspective since they don't have to understand the timing of
when a SurfacePackage is attached vs when a view gains focus.

Test: SurfaceControlViewHostTests
Bug: 230340812
Change-Id: If55b33e92769e37794bd258e7f41da40decbef8c