Add Flashblocks RPC module #188
Description
With the new revert protection mechanism, the eth_getTransactionReceipt endpoint of the builder can return an error if the transaction was dropped from the private memory pool.
On parallel, for Flashblocks, we have introduced a new Flashblocks RPC Reth client flavour that can consume the stream of preconfirmed information and return it to the user. This RPC overlay extends the eth_getTransactionReceipt endpoint too.
Ideally, we want to have both functionalities on the server that resolves the eth_getTransactionReceipt endpoint, but, as of now, it is not possible in the short term to notify the Flashblocks RPC overlay of updates in the private memory pool.
Thus, this issue proposes bring the RPC overlay functionality into the builder itself. The current implementation of the Flashblocks overlay has been implemented in a modular way here so that it can be included in any service that provides a stream of the Flashblocks preconfirmed data, and, that is something that the builder can provide.