[CA-155888] add a query reservation id interface
[CA-155888] add a query reservation id interface

Signed-off-by: Chunjie Zhu <b82540d5adc307d29b9d1f6c399290c203437b16@citrix.com>

Chunjie/xcp-idl,djs55/xcp-idl,johnelse/xcp-idl,xapi-project/message-switch,xapi-project/message-switch,euanh/xcp-idl,xapi-project/message-switch