Support Resume on Reboot

When an OTA is downloaded, the RecoverySystem can be triggered to store
the user's lock screen knowledge factor in a secure way using the
IRebootEscrow HAL. This will allow the credential encrypted (CE)
storage, keymaster credentials, and possibly others to be unlocked when
the device reboots after an OTA.

Bug: 63928581
Test: make
Test: boot emulator with default implementation
Test: boot Pixel 4 with default implementation
Change-Id: I1f02e7a502478715fd642049da01eb0c01d112f6
diff --git a/private/service_contexts b/private/service_contexts
index dd71111..4399ea4 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -1,3 +1,4 @@
+android.hardware.rebootescrow.IRebootEscrow/default u:object_r:hal_rebootescrow_service:s0
 android.hardware.vibrator.IVibrator/default u:object_r:hal_vibrator_service:s0
 
 accessibility                             u:object_r:accessibility_service:s0