Pybricks 4.0 slot support

[mori-la]

When uploading a program, it is uploaded into the current slot on the Spike, but slot 0 is started.

When using #LEGO slot:x it is uploaded into the current slot on the Spike, but slot x is started.

[afarago]

Nice catch @mori-la .

I have fixed starting the right (selected) slot for pybricks hubs.
Not yet published - if you can compile and test - would be happy for a feedback.

While uploading I have no control on the slot - selectedslot is a limitation from Pybricks side.
You might suggest an improvement on the protocol to allow selection of upload slot programatically to Laurens - through the pybricks support pages/repo.

[kai-morich]

It is working with your change.
Tested with #20