Allow operating a builder with no fee and no payout TX

[krasi-georgiev]

Rationale

Why should this feature exist?

• when the builder doesn't collect any fee it is very enificient to create a payout TX on every block.
  some validators use a contract which consumes 70-100k gas so without the payout TX the total block value will be higher.

What are the use-cases?

• operating a builder that doesn't collect block fees.

Implementation

Do you have ideas regarding the implementation of this feature?

• yes
  the simulation checks -
  • if the coinbase address is the same as the validator's address
  • the coinbase balance difference is the same as the bid value

Are you willing to implement this feature?

• yes

[krasi-georgiev]

cc @Ruteri

[krasi-georgiev]

moved to flashbots/mev-boost#419