feat: add support to ETH2

[aldoborrero]

Closes #8

[aldoborrero]

@brianmcgee several notes to add:

• We're just running an Execution Node + Beacon Node. At this stage, I don't consider it helpful to add either the validator or the slasher service (and among those, only validator is more critical compared to slasher).
• We're running on the testnet Sepolia. This testnet has migrated to PoS, and as it's recently, we can sync faster than Goerli.
• I tested combinations with Geth + Prysm, and although it worked fine, it took more time to sync properly. On the other hand, erigon goes fast enough and doesn't consume too many resources.
• I moved eth1 version to docker-compose.eth1.yaml.
• Added two new shortcuts to just: up & down. Those should be used to properly spin up the dev environment.

Once erigon + prysm is running, in order to verify that everything is working fine:

For checking the node has stopped syncing and is ready:

➜  tethys git:(feat/eth2-support) http http://localhost:3500/eth/v1/node/syncing
HTTP/1.1 200 OK
Content-Length: 91
Content-Type: application/json
Date: Wed, 31 Aug 2022 14:17:43 GMT
Vary: Origin

{
    "data": {
        "head_slot": "518488",
        "is_optimistic": true,
        "is_syncing": false,
        "sync_distance": "0"
    }
}

For knowing if it's fully initialized:

➜  tethys git:(feat/eth2-support) http http://localhost:3500/eth/v1/node/health
HTTP/1.1 200 OK
Content-Length: 0
Content-Type: application/json
Date: Wed, 31 Aug 2022 14:18:20 GMT
Vary: Origin

Code 200 means node is ready.

What is Sepolia?

How is Sepolia different from other testnets?

The difference between Sepolia and other Ethereum testnets is that Sepolia is a public testnet run mostly by public validators in contrast to testnets like Kovan, where only 4 sets of validators are approved.

These public validators who have not undergone any background check or capability testing by network participants, could possibly fail to have the necessary hardware and software to stay connected to the testnet at all times, and hence cause the chain to fail to finalize.

Over the long-term future the Ethereum team plans on only maintaining the Goerli testnet and maintaining the Sepolia testnet, who’s chain ID is 11155111.

[brianmcgee]

Review in progress

[brianmcgee]

LGTM