Add a builders blacklist for ePBS

[potuz]

We need to keep a blacklist of builders to not take bids from and not gossip bids from. Otherwise a single builder can poisson the p2p stack by submitting high bids. This cache needs to be checked against crucially in two places

• SignedExecutionPayloadHeader gossip validation
• Block proposals.

[shyam-patel-kira]

We need to keep a blacklist of builders to not take bids from and not gossip bids from.

How do we decide on which builders should be added to this blacklist?

Edit: Reply from terence: it's subjective and more of an open design. Example: builder revealed an invalid block. Builder revealed a late block under observation. Buildn't revealed a valid block but didnt reveal any blobs... etc