Support ART on-device testing in a chroot environment.

This change updates the ART test rules and scripts to allow
installation and ART testing in a chroot directory on device.

All existing ART testing is supported:
- ART gtests (with and without Valgrind).
- ART run-tests.
- libcore tests (with companion CL in external/vogar).
- JDWP tests (with companion CL in external/vogar).

Test: Run ART tests (gtest, run-tests, libcore tests, JDWP tests) in chroot
Bug: 34729697
Bug: 68125496
Change-Id: I398e9bafee61eccd98d827ab8d9b8f6395aaa853