merge support for kasli-soc

[jbqubit]

This is a place to discuss (and track) merging support for kasli-soc with the ARTIQ codebase. This was previously mentioned here.

Currently the dependent code is in several places.

• Zynq port of ARTIQ [link]
• Bare metal support for Zynq [link]

M-Labs (@sbourdeauducq) comments so far include the following.

• Gateware is easy to merge and most of it is just importing from ARTIQ anyway.
• The firmware for Zynq (NAR3) is more modern than the one for RISC-V devices. It should eventually be ported to RISC-V and replace it. But this is a difficult project with objectively little pay-off, so this is not high on the priority list at the moment.