Automated monitoring of continuous fabric drops

On supported platforms, the system automatically monitors fabric drops. If detected, the platform adds a syslog entry with fabric queue information and raises a minor error in the chassis management module. Errors include CM_CMERROR_FABRIC_LO_PRI_Q_DROP, CM_CMERROR_FABRIC_LO_PRI_Q_DROP_ALL, CM_CMERROR_FABRIC_HI_PRI_Q_DROP, and CM_CMERROR_FABRIC_HI_PRI_Q_DROP_ALL