New FPGA image possibly needed for Cosmo Rev B

[ericaasen]

Issues such as https://github.com/oxidecomputer/hardware-cosmo/issues/691 caused FPGA pinouts to change. This issue tracks the need to do this.

[nathanaelhuffman]

fwiw, I'm going to attempt to keep them the same and use resistor strapping to mux new stuff in. We'll see, if in practice this becomes too confusing or problematic, that may necessitate a split

[mkeeter]

Sounds good; Hubris will almost certainly have a new rev-b image, so it's no problem either way on the Hubris side.