Added response fields & request parameters for plan details.

New response and request fields


## Changed

- New `plan_zoom_one_edu_student`, `plan_zoom_one_edu_school_campus_plus`, `plan_audiof, plan_zoom_one_edu_premier`, and `plan_package_lists` response fields in this Billing API:
  - `GET /v2/accounts/{accountId}/plans`
- New `plan_ai_expert_assist` response field in these Billing APIs:
  - `POST /v2/accounts/{accountId}/plans`
  - `GET /v2/accounts/{accountId}/plans`
- New `hosts, hosts`, `plan_ai_expert_assist`, `plan_package_list`, `callout_countries`, `callout_countries`, and  `plan_package_list` request fields in this Billing API:
   - `POST /v2/accounts/{accountId}/plans`
- New `partner_sku` response field in these Billing APIs:
  - `POST /v2/accounts/{accountId}/plans`
  - `POST /v2/accounts/{accountId}/plans`

