Changes to List subscriptions.

the endpoint scheme security BearerAuth AND DeveloperIDHeader was added to the API

the response property list/items/subscribed_at became optional for the status 200

for the query request parameter page, the format changed from int64 to int32

for the query request parameter page_size, the format changed from int64 to int32

the status response's property default value 400 was removed for the status 400

the status response's property default value 401 was removed for the status 401

added the new 400.00 enum value to the status response property for the response status 400

added the new 401.00 enum value to the status response property for the response status 401

the status response's property default value 400 was added for the status 400

the status response's property default value 401 was added for the status 401