* Local sim impovements
* Added support for running Capella and EIP-4844 simulations
by downloading the correct version of Geth.
* Added support for using Nimbus remote signer and Web3Signer.
Use 2 out of 3 threshold signing configuration in the mainnet
configuration and regular remote signing in the minimal one.
* The local testnet simulation can now use a payload builder.
This is currently not activated in CI due to lack of automated
procedures for installing third-party relays or builders.
You are adviced to use mergemock for now, but for most realistic
results, we can create a simple builder based on the nimbus-eth1
codebase that will be able to propose transactions from the regular
network mempool.
* Start the simulation from a merged state. This would allow us
to start removing pre-merge functionality such as the gossip
subsciption logic. The commit also removes the merge-forcing
hack installed after the TTD removal.
* Consolidate all the tools used in the local simulation into a
single `ncli_testnet` binary.
zah