[Spike] Address EWT Implementation Concerns

Address these concerns before proceeding to implement EWT Calculation

1. Average Talk Time Calculation:
   1. What is time bracket to calculated Average Talk Time? e.g. 24 hours, 1 week, 1 month or start of time (full historical data) ramzan.shah we need to keep it configurable see CSN-1159
   2. Where it should be maintained? e.g. fetching Avg Talk Time from Reporting DB upon every new task arrival, maintenance and calculation of Avg Talk Time in MRE's memory

• need to check how Cisco manages EWT (Check Cisco Unified Queue API)