Add storage test boilerplate.
Add storage test boilerplate.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@eu.citrix.com>

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