Cosmo seq Bring-up running TODOs

[nathanaelhuffman]

While trying to get the bones all wired up in cosmo seq, I've taken a few shortcuts that I don't want to forget about. We need this functionality before bring-up. This also acts as documentation in case something happens to me and someone else is left staring at my project.

None of this is that complicated but it may be tricky to find at first glance.

• Add synchros for all inputs into sequencer bock, currently not sync'd at all!!
• Add sequencer simulations and models for rails etc. Lots of nicer work can be done here to have robust coverage of things.
• Fix up m.2 PERST logic, probably wants a 1-shot, currently bonded to power enable.
• Add early power registers and control of the hotswap disables for the fan controller.
• Need to "reset" the hotplug blocks upon A0 domain power down.
• Need to wire up "reset" control of i2c muxes
• Need to wire up exclusivity of i2c muxes
• Need overrides for SP5, NIC signals
• Need to wire up SP5 UART0 mux out to FPGA pins for DDR training
• Need to determine what software/hw we want/need to do peek-poke into the fpga. Can we get away with just hubris? (hubris-only is the plan)
• SP5_TO_FPGA1_DEBUG1 driven high at sequence time for como sp5 identification
• Need to get T6 and sidecar hotplug stuff connected to rear "PCA"
• Need some form of SPD proxy
• Consider some kind of interface to the front FPGA?