Changes to Read an existing Campaign.

added the new CTV_WEB_USER_ACQUISITION enum value to the campaign/type response property for the response status 200

added the new LEARNING enum value to the campaign/state response property for the response status 200

the response optional property campaign/ad_account_id became not read-only for the status 200

the response optional property campaign/product_id became not read-only for the status 200