Optional FW driven readout for v3

Different scripts for SW-driven or FW-driven readout. Stable main version until 13 August 2024. No compatibility with v4.

What's Changed

• Use FW-driven readout by @c235labtop in #9
• Update spi.py by @c235labtop in #10
• config value updates by @c235labtop in #15

Full Changelog: readout_SWdriven...readout_FWdriven_optional

SW driven readout with v2 and v3 compatibility

Bench testing setup for single v2 or v3 chips mounted to PCBs that interface via PCIe with the GECCO board. Digital data is read off the chip by python scripts (such as beam_test.py) monitoring the interrupt line, sending the FPGA write bits when the interrupt is low, and reading data from FIFO to clear the buffer.