Add Vouch validator client

[corver]

Problem to solve

Charon states it supports Vouch validator client. But this hasn't been tested or confirmed yet. This repo also only had teku and lighthouse.

Proposed solution:

• Add Vouch as VC for node3.
• A single node Vouch is all that is required (not multi-node).
• First prize is implementing it the same as teku (without a folder or run script), just a docker-compose service.
• Remember to configure network as auto, since charon can connect to prater/gnosis/kiln/simnet/devnet.
• Remember to load the keys on startup.
• If this is not trival, like lighthouse, a folder and run script can be added.
• Try to keep everything to the absolute minimum

[Oisín Kyne]

Finish this PR #35