Pass app version to agent in adb restore for kv.

This is a temporary solution for P to unblock GTS tests.

Bug: 77852250
Test: manual:
1. adb backup -f saved-wifi-api100.ab -keyvalue com.android.providers.settings
2. adb restore saved-wifi-api100.ab
3. See that SettingsBackupAgent receives appVersionCode in onRestore()

Change-Id: I6092bea570e7e27cb5b72165e9284ad2befc21b6