Moved emulated User HAL capabilities into a library.

So it can be used by other Vehicle HAL implementations.

Test: adb shell lshal debug android.hardware.automotive.vehicle@2.0::IVehicle/default --user-hal
Test: adb shell lshal debug android.hardware.automotive.vehicle@2.0::IVehicle/default --help
Test: m -j android.hardware.automotive.vehicle@2.0-emulated-user-hal-lib

Bug: 150167241
Bug: 150409377

Exempt-From-Owner-Approval: already approved on rvc-dev, need to submit here due to merge conflict

Change-Id: I2d0c5039c3b994dfe10d3b411f6d502bebe7cca0
(cherry picked from commit 1847a9b25e191c8258522f30b6d4223458feebd1)