WES cannot handle configuration change of dbroot count without restart

Related to MCOL-3999 discovered when failover was trying to reinit WES and not restart.
FileOp::initDbRootExtentMutexes( )
only creates mutexes for dbroots the first time its executed and only creates mutexes
if m_DbRootAddExtentMutexes.size() == 0
This means that if a dbroot is added to a module and WES is not restarted you will see this error in logging:
Jun 12 11:32:31 testPM3 writeengine[16121]: 31.763854 |0|0|0| E 19 CAL0001: we_readthread caught exception boost unique_lock has no mutex: Operation not permitted

Proposed fix is to check if number of dbroots is not equal to number of extent mutexes and reset and rebuild if a change is detected.