Use system property for payload metadata

Bug: 191097666
Test: atest apexd_test.cpp
banchan com.android.virt aosp_arm64
m apps_only dist
adb install out/dist/com.android.virt.apex
adb reboot

Change-Id: I6f1223d5750caeb99dc2265e6f28afed08dbcdf4
4 files changed