Add sapling support to btchip-python

[ghost]

At the very least, I think p2 here needs to be 0x05 for sapling transactions (And in the subsequent uses);

https://github.com/LedgerHQ/btchip-python/blob/7c6d107d0ec2e55484c39849ff9291167cf41fd0/btchip/btchip.py#L217

But I'd rather check with someone more familiar with this code on the best approach before PR.

I tried it out and it seems to crash the device and disconnect the USB, but that could be to do with the subsequent calls. I'm working on setting up debugging