Support basic auth in beacon.Client [regression]

[theexoticman]

Describe the bug

The beacon.Client hostname handling does not extract username and password from basicauth, so the request to an execution client protected by a reverse proxy using basic auth will fail.

Has this worked before in a previous version?

Yes - ref: #10632

🔬 Minimal Reproduction

~/consensus/dist/beacon-chain-v5.0.3-linux-amd64 --execution-endpoint=http://$USERNAME:$PASSWORD@toto.com --sepolia --jwt-secret=~/consensus/jwt.hex --checkpoint-sync-url=https://sepolia.beaconstate.info --genesis-beacon-api-url=https://sepolia.beaconstate.info

Error

[2024-04-05 18:09:22] ERROR execution: Could not connect to execution endpoint error=could not verify execution chain ID as your connection is not authenticated. If connecting to your execution client via HTTP, you will need to set up JWT authentication. See our documentation here https://docs.prylabs.network/docs/execution-node/authentication: 401 Unauthorized: 401 Authorization Required

401 Authorization Required
==========================

* * *

nginx/1.18.0 (Ubuntu)

 
 
### Platform(s)
 
Linux (x86)
 
### What version of Prysm are you running? (Which release)
 
v5.0.0 - v5.0.3 and maybe before
 
### Anything else relevant (validator index / public key)?
 
_No response_