Implement other sampler bit widths

Hardcode to use 4 bit sampling for now.
Add debug prints using module_uart_print
Fix compilation: add uart_print header
Move control proto to endpoint 0

- Use control transfers to endpoint 0;
- Free up one thread, used to implement control proto
Handle sigrok driver rename xmos-la -> xs1la
#ifdef debug prints
Provide commands to get hardware and firmware info