Use try lock to fix class resolution race

There was some possible deadlocks related to EnsureResolved caused by
acquiring an object lock.

Scenario:
Thread 1 acquires lock on obj1
Thread 1 begins to resolve / initialize class1
Thread 1 blocks since it sees that class1 is already being resolved and
gets preempted before it can acquire the object lock on class1
Thread 2 finishes resolving and initializing class1 and locks class1
Thread 2 blocks attempting to lock obj1
Thread 1 blocks attempting to lock class1
Deadlock

Fixed the deadlock by changing EnsureResolved to use a try lock for the
unresolved case.

Added a test.

Test: Device boot, test-art-host, monitor_test

Bug: 27417671

(cherry picked from commit a704eda0)

Change-Id: I1150b19bdc1a5cc87ae95eda4f2b6b4bca215a60