JFR: Java Monitor Enter

[tajila]

Add support for the JavaMonitor[Wait|Enter] event:

JavaMonitorEnter fields
- startTime
- duration
- eventThread
- stackTrace
- monitorClass
- previousOwner
- address

In objectMonitorEnterBlocking the J9HOOK_VM_MONITOR_CONTENDED_ENTERED will be used to trigger the event. New fields will need to be added to capture the monitorClass, address and previous owner.

MonitorClass - can be determine with J9OBJECT_CLAZZ(object)
Address - addr of object
PreviousOwner - If not inflated, can be determined by reading lwEA and clearing the locking bits (OBJECT_HEADER_LOCK_RESERVED, etc.). If inflated, can be determined by `((J9ThreadMonitor*)monitor)->owner)

[tajila]

@adpopescu Please take a look