Improve headless system user's DO setup flow

1. Change manageUser to be setup on current user
2. add pre condition check for headless system user mode: disallows setup when current user is system user 0 and only allows device owner to be set on user 0
3. Changes method name and adds param names

To verify:
1. Install TestDPC app: https://github.com/googlesamples/android-testdpc
2. make sure device is unprovisioned
adb shell dumpsys device_policy
2'. deprovion if needed
adb shell settings put global device_provisioned 0 && adb shell rm /data/system/device_owner_2.xml /data/system/device_policies.xml
3. make sure deivce_amdmin feature is available
 adb shell pm list features | grep "admin"
3'. install feature if needed
adb push frameworks/native/data/etc/android.software.device_admin.xml
/vendor/etc/permissions/
4. run
adb shell dpm set-device-owner --user 0 com.afwsamples.testdpc/com.afwsamples.testdpc.DeviceAdminReceiver
5. verify with
adb shell dumpsys device_policy
6. try to set on user 10 will fail
adb shell dpm set-device-owner --user 10 com.afwsamples.testdpc/com.afwsamples.testdpc.DeviceAdminReceiver
6. switch to user 0, repeat 4. It shall fail.

Bug: 170333009
Bug: 174610623
Test: manual with steps above
Change-Id: Iaa46032fa6487d792f7bde5de5ff6e55b9c36432