Introduced a new Report API for retrieving engagement variables. Enhanced existing Report APIs with additional request and response fields to provide richer engagement and query detail insights.

Expanded reporting APIs for virtual agent insights


## Added
- New **Report** API:
	- `GET /v2/virtual_agent/report/engagements/variables`
### Enhancements
- New `interaction_duration,skills,interaction_turns,articles,topics,last_responder,agents,tools` response fields in the following  **Report** API:
	- `GET /v2/virtual_agent/report/engagements`
- New `agent_type,agent_session_id,helpful_response,topic_name,agent_name,agent_id` response fields in the following  **Report** API:
	- `GET /v2/virtual_agent/report/engagements/query_details`
- New `agent_types` request field in the following  **Report** APIs:
	- `GET /v2/virtual_agent/report/engagements/query_details`
	- `GET /v2/virtual_agent/report/engagements`
