Charon can aggregate

[OisinKyne]

Problem to be solved

We have outlined a new endpoint for the beacon api here. We want to prove this proposal will work before we lean heavily on client teams to implement it (particularly into their VC side, not their BN side)

Proposed solution

Build this endpoint into our validatorAPI, and add the needed code to make this happen to go-eth2-client.

Use either a forked vouch (or LH or Teku) to produce a valid aggregation on a goerli testnet.

Out of Scope

Having a prod-ready validator client that uses this endpoint, this can be an ugly hack fork that gets thrown away.

[corverroos]

Here is the design doc: https://docs.google.com/document/d/1_J8Y9M4FsONmEENSPwzzZW9n_zrnmAPGoSO2sm6DIO8/edit#

Note this is more of an epic, since it includes two new duties and touches all components including one new component.