New event to signal to builder that bid was accepted?

[nflaig]

Based on some discussion I had with @rolfyone we might need an event for gloas that allows a CL client that "acts as a builder" to know whether the bid was accepted and included in a block by a proposer without having to subscribe to gossip, or alternatively listen to block event and call getBlockV2 to inspect the contents. A simple fix would be to include the builder index in the block event but that requires adding a field, which should be no issue but need to see if people are happy with this.

[nflaig]

as discussed with @bharath-123, we might want to extend the existing block event to also include the block_hash (as committed in the bid) and builder_index to make it useful for builders to know whether or not their bid was included by a proposer