Implement config page

[remyroy]

That would be the fourth page named Install Ethereum 2.0 on the figma mockups. This is the page where you select the Ethereum clients and the installation path.

Depends on #80

[remyroy]

There are discrepancies between what is offered with eth-docker and what is shown in the mockups. We have a lot of options and advanced configuration settings we can offer if you look at the default.env file for instance.

Here are the essential options we should be offering:

• Execution client (Geth, Erigon, Besu or Nethermind)
• Consensus client (Teku, Lighthouse, Nimbus, Lodestar or Prysm)

Advanced options that are very insteresting to see:

• Execution client fallback endpoint
• Initial state/checkpoint endpoint
• Installation path