Inject an Unknown Fault instead of aborting VM on unknown exception

This allows the VM to decide how to handle the fault, rather than being
forcefully aborted.  It also allows us to simplify some of the secondary tests,
whereby the test can trap and observe the exception rather than abort, which
reduces the number of secondary VM services tests need to spawn.

Bug: 140916188
Change-Id: Ib2e98a6507aa15c5d805089cd28851b66c6a6379
22 files changed