Show XInput slot in the ControlApp for connected DsHidMini devices in XInput mode

[Kanuan]

Some games that support XInput controllers depend on controllers being in specific XInput slots to work properly.

There are ways to discover which XInput slot any connected XInput controller is currently, but having it on the ControlApp will make this info easily accessible for the average user.

[nefarius]

This helper function could be ported to C# for this feature.