dcache-qos (10.3): pool operation map and counters

Motivation:

Refactor resilience service into QoS components,
adapting and adding functionality to support extended
QoS policy management and handling.

Modification:

Adds the core map which holds the operations
for each registered pool.

Result:

Parts 18 / 31 of QoS refactoring.

Target: master
Patch: https://rb.dcache.org/r/12993/
Acked-by: Tigran