Expose getEntityLockMonitor in the MBean EntityLockMonitorMBean

In order to perform proper monitoring of EJB locks, the current functionality is not enough for the following reasons:

1. The LockMonitor is saved per EJB name, where multiple EJBs can have the same name. The solution should be to store it based on the jndi name.
2. The only way to get per-EJB information is to use the printLockMonitor method. This will create a non reasonable overhead for a real-life monitoring solution. The solution here is to expose the method getEntityLockMonitor in the MBean interface.