Changes to Create an agent

added the new optional request property endclose_writes

added the optional property endclose_writes to the response with the 201 status

the response property model became nullable for the status 201

added the optional property browser to the response with the 201 status

added the optional property kind to the response with the 201 status

added the new agent enum value to the mentions/items/type response property for the response status 201

added the new agent enum value to the request property mentions/items/type

endpoint added