Enhance participants on games API to be more granular

[JonRay15]

Issue

Look at https://darling.network/api/v2/games

For "participants" we are just showing a single number which appears to be the number of actual keys paid in a game ... this is not right for a few reasons.

To make this clearer I think we should show multiple things here and then we can choose which to use in the appropriate case.

Proposal

Show

1. Number of paid entities - where entity is set by the entity scope, ie. if it is a team game show the number of participating teams, if its a individual game the number of participating individuals
2. Number of paid keys - ie. in a team game this would count the actual paid players in those teams, in individual game it would be unchanged
3. Number of eligible entities - currently we are ONLY showing paid entities, which is misleading because there are various teams which are "playing" and meeting the eligibility criteria but have performed poorly and therefore not been rewarded. Ideally we would show all entities which have met the criteria as "participating"
4. Number of participant keys - so this would be the same as above but for every key single key

[JonRay15]

I cant really recall what this is ... so it cant be that important ... happy to move it to Genbu