Add GNO support: would be nice if Siren detected the validators network and adjust the token in the UI accodinly

[mjadach-iv]

Is your feature request related to a problem? Please describe.
With the newest Siren and Lightouse ruinning and validating Gnosis network, you can see stats for ETH and not GNO with wrong values. It probably is showing mGNO (1 mGNO = 1/32 GNO) as ETH, but it would be nice to see the actual balances, you normally would.

Describe the solution you'd like

1. Detect the validator network
2. Switch the token from ETH to GNO
3. Adjust the balance (in Gnosis case, probably divide the balances by 32?)
4. Take the price of GNO (or other netowork staking token) instead of ETH for the FIAT conversion in the UI
5. Add information about it to the docs here or the FAQ: https://lighthouse-book.sigmaprime.io/ui_faqs.html

Additional context