Started implementing nixie_display set_digit driver

Added remainder of the DIGIT_MAP

Started nixie_display driver that abstracts the shift register writes to direct digits on the tubes.

Realized I got my tube naming backwards. Updated schematic with correct naming annotations

Set SPI periph in mode 1. CPOL = 0 and CPHA = 1 to clock data out on falling edges.

Added some wrapper functions for the blanking and polarity pins

Driver started

Updating SPI data size to 8bit

Adding clang format

updated hv5622 driver to use SPI and GPIO periphs