Changes to Batch Amend Orders

added the new required request property request/items/qty

the request/items/price request property type changed from integer to string, and format from int64 to no format

the response property result/items/order_id became optional for the status 200

added OrderId subschema #1 to the result/items/order_id response property oneOf list for the response status 200

the result/items/order_id response's property type changed from string to no type, and format from uuid to no format for status 200

removed the request property request/items/size

added the new optional request property await_outcome

endpoint added