list: Implement RPC calls for virConnectListAllSecrets

list: Implement RPC calls for virConnectListAllSecrets

The RPC generator doesn't support returning list of object yet, this patch
does the work manually.

  * daemon/remote.c:
    Implement the server side handler remoteDispatchConnectListAllSecrets.

  * src/remote/remote_driver.c:
    Add remote driver handler remoteConnectListAllSecrets.

  * src/remote/remote_protocol.x:
    New RPC procedure REMOTE_PROC_CONNECT_LIST_ALL_SECRETS and
    structs to represent the args and ret for it.

  * src/remote_protocol-structs: Likewise.