node: Add graphman query

[lutter]

This makes it possible to execute a GraphQL query with

graphman query sub/graph '{ .. GraphQL .. }' var1=val1 ...

By passing GRAPH_LOG_QUERY_TIMING=gql,sql GRAPH_LOG=debug in the environment, the command will log a lot of info about query execution.

For now, it's probably best to not run this against production directly though. Amongst other things, the code sets up notification listeners as a side-effect of creating the store.

[leoyvens]

Should this print a warning about the notification listener and not running it against prod?

[lutter]

Should this print a warning about the notification listener and not running it against prod?

I think the real solution is to change the code to not set up notification listeners by default; I think all that is needed is getting the ChainHeadUpdateListener our of the ChainStore - it really has no business being in there anyway, and is just used as a convenience to make it easier to pass both the listener and the store around.

[leoyvens]

Got it, if we want to merge as is and improve later, fine by me.