Add global property to store opt-in application package name.

We provide a way in developer option to opt-in an application to use updated
graphics driver. To make sure we set up the graphics environment correctly, we
need to access the package name of the selected application. This patch
introduces a global property to store the package name.

BUG: 119221883
Test: Build, flash and boot, verify with prototype
Change-Id: I49dfcccf387169c072fb9345f7a50c00fcdb0737
Merged-In: I49dfcccf387169c072fb9345f7a50c00fcdb0737