Retrieve engagement histogram data for a webinar. Returns arrays of
per-time-bucket counts for attendees, chat activity, and visual focus,
useful for rendering engagement visualizations.

Requires api token with one of the following permissions

Read detailed stats

Tokens with the "Act with a team member's permissions" permission
(all:delegate_to_contact_permissions scope) can also be used. Requests
made with such a token are authorized using the permissions of the
contact assigned to the token.

An expiring access token
created with the all:delegate_to_contact_permissions scope and an
authorization granting the view-stats permission on this webinar can also
be used.