Adding Staging Environments For Every Subgraph

[jiro-ono]

We need staging environments for every subgraph.

Not sure if there is an actual staging environment for each subgraph. Found this pattern in package.json
of the uniswap-fork. If there isn't a staging environment, then just having staging subgraphs would be helpful and scripts to deploy them to their respective locations.

`"deploy-staging": "graph deploy $THE_GRAPH_GITHUB_USER/$THE_GRAPH_SUBGRAPH_NAME --ipfs https://api.staging.thegraph.com/ipfs/ --node https://api.staging.thegraph.com/deploy/",