FOCIL fork choice changes

[michaelsproul]

Description

• Import valid IL's & equivocating IL's to the fork choice store
• Handle unsatisfied_inclusion_list_block logic

[michaelsproul]

I think the spec may be missing changes to get_proposer_head. It seems like (on time) IL-invalid blocks would not actually get reorged, because there are no changes to the proposer's choice of head to build upon. Currently the single-slot reorg strat only kicks in when the block is late.

We should probably raise a spec issue for this.

[michaelsproul]

Case of two IL-invalid blocks in a row is also a bit strange with my understanding of get_attester_head, which always nominates the parent of the LMD-GHOST head

[michaelsproul]

Asked these questions here: https://discord.com/channels/595666850260713488/1210529202458071050/1328595006877077534