Compile standalone system server jars.

This CL updates odrefresh to take an additional environment variable
`STANDALONE_SYSTEMSERVER_JARS` and compile standalone system server jars
accordingly.

Bug: 203198541
Test: atest odsign_e2e_tests
Test: atest art_standalone_odrefresh_tests
Test: atest art_standalone_artd_tests
Test: manual -
  1. Patch aosp/1874113, aosp/1876173, aosp/1875774 and aosp/1875775.
  2. Build a new system image and flash it to a device.
  3. adb logcat odrefresh:D odsign:D "*:S"
  4. See standalone system server jars being compiled and signed.

Change-Id: Ic824c7380cf9530437bc2a95b9ff816a63b22013
12 files changed