[Feat.Req] Add query for current POI state

[pete-eiger]

Problem statement

For a given Subgraph deployment, we want to display the current POI
state - who is attesting, what the groups are, what the "consensus POI" is, etc.

Expectation proposal
After these Issues are completed - #122 & #130 , we need to make sure all the data for this use case is served by the GraphQL API. Most of that will be covered by work for this Issue - #124, however we would still need to add CONSENSUS_PPOI as a metric.

(This issue description will be enhanced when the Issues mentioned above are completed)