L2 aware subgraph

This release includes some basic L2 aware features, like total GRT deposited/withdrawn from L2 (although only one is visible at a time, given that deposits are visible from a deployment on L1, while withdrawn is only visible from a deployment on L2).

It also includes a refactor to the github workflows due to multiple changes (rinkeby deprecated in favour of goerli, L1/L2 deployments per environment, etc).