Add delegations to some validators running the Bolt sidecar

[thedevbirb]

Currently we have only one beacon node with 64 validators attached that run the Bolt sidecar using the keystore. Ideally, we should have another one that runs via delegations so that we can test both flows in the devnet.

We have two approaches for this task. One is invoking the bolt-cli tool inside the Ethereum package and compute the delegation on the spot; the other relies computing them before hand since the mnemonic is known and keys are generated deterministically.

The second approach is faster but less flexible compared to the first one which can be more granularly configured.