Added new response fields: *forward id* in Reports APIs for chat sessions and *is external* in Chat Channels API to indicate external channel admins.

Enchancements made to Reports and Chat Channels APIs


## Added

### Enhancements

- New forward_id response field in the following  Reports APIs:
    - `GET /v2/report/chat/sessions/{sessionId}`
    - `GET /v2/report/chat/sessions/{sessionId}`
    - `GET /v2/report/chat/sessions/{sessionId}`
- New is_external response field in the following  Chat Channels (Account-level) API:
    - `GET /v2/chat/users/{userId}/channels/{channelId}/admins`
