CPS-1953 Compare Active Subscriptions (DB) with the current request

1. Compare Active Subscriptions (DB) with the current request
   1. Find delta
      • we have the same subscription if we have the same combination of 
        1. cmhandle AND xpath filter AND datastore
   2. Create structure to hold all 'PENDING' subscriptions
      1. HZ map
   3. Update when there's overlapping
      • updating the status in the HZ map from 'PENDING' for duplicated request(s)

A:

Active Subscriptions model imported from Database

Wide Net → Narrow Net method

B:  

Reuse CmSubscriptionCacheObject model to store "PENDING" subscriptions

 IMap<String, CmSubscriptionCacheObject> pendingCmSubscriptions

Map of Subscription Id and  CmSubscriptionCacheObject

C: