Add sapling support to btchip-python

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

btchip-python/btchip/btchip.py

Line 217 in 7c6d107

apdu = [ self.BTCHIP_CLA, self.BTCHIP_INS_HASH_INPUT_START, 0x00, p2 ]

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