Use IPFS version of network subgraph

[Theodus]

I previously avoided using network subgraph features requiring IPFS support (here). The network subgraph has been refactored to use deterministic IPFS data sources. So we can use SubgraphVersion label directly rather than fetching the metadata payload ourselves, even after the network subgraph is depolyed to the network.

[Theodus]

superseded by #455