Signed-off-by: Daniel Golle <daniel@makrotopia.org>

Detect if calling rpc-sys packagelist fails due to the method not
being provided by rpcd.
Mark package as experimental.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

The Attended sysUpgrade CLI is a full-featured client for the
attended-sysupgrade service which works directly on the target device.
It requires libustream-ssl as well as at least the CA certificate
needed to contact the sysupgrade server.

It has only been tested briefly and is by no means ready for
production!

Signed-off-by: Daniel Golle <daniel@makrotopia.org>