feat(indexer-service): Add graph-node version endpoint from status api

[abarmat]

The graph-node is exposing the version information using the following struct, however, it's not exposed through the indexer-service status endpoint.

This PR adds that information so that the gateway can have access to it.

struct Version {
    version: String,
    commit: String,
}

[Theodus]

Ideally this would be surfaced via /version. But it's more important that this gets to indexers ASAP so that we can start enforcing a graph-node feature set.

[fordN]

👍