create unified slashing cache

[realbigsean]

Issue Addressed

#5017

Changes

• added a new slashing cache, to track slashing across all messages
• simplified the blob gossip cache, so it no longer tracks block roots
• I initially simplified the block gossip cache as well, but it turns out we still need to distinguish between "blocks failing gossip that are slashable" and "blocks failing gossip that are duplicates" so that we can correctly suppress the duplicate error code
• Additionally, this makes sure we add slashable headers from blob sidecars received via RPC. And checks the signatures. (I don't think we were checking the signature before sending it to the slasher before).
  • I've also opted not to throw error when the signature is invalid here (which would result in not importing the blobs even if the data is correct, and would lead us to downscore the peer), because on an RPC request we only really care whether the data is available or not

[michaelsproul]

Nice, I can't spot any issues with this.

I'm trying to think of ways to simplify it further, as it would be great to remove observed_block_producers and just use observed_slashable for all blocks. I think this would require tweaking the spec conditions however, and a resolution to questions like should we propagate slashable messages in a limited way? (ethereum/consensus-specs#3561).

[realbigsean]

Thanks for the review!

I'm trying to think of ways to simplify it further, as it would be great to remove observed_block_producers and just use observed_slashable for all blocks. I think this would require tweaking the spec conditions however, and a resolution to questions like should we propagate slashable messages in a limited way? (ethereum/consensus-specs#3561).

I agree. If we can re-use the definition of "equivocation" from broadcast_validation in gossip we could simplify this pretty well. But I brought it up on a call and I don't think there's appetite for it until post-deneb.