Creates a new webinar.

Requires api token with one of the following permissions

Read, update & delete anything

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
account authorization granting the create-webinars permission can also
be used. The new webinar is not covered by the token that created it, so
follow-up requests need a token whose authorizations name the returned
hashed id.