[nis] add endpoints that will return max, total, circulating supply

[cryptoBeliever]

Current Behaviour

To integrate with some external services (like Coinmarketcap) is it required to have endpoints to return supply (max, total, circulating). For now, NIS API doesn't have such endpoints.

Expected Behaviour

NIS API should have an endpoints (according Coinmarketcap requirement it should be separate endpoint for each property) to return supply:

• max
• total
• circulating

For now, it should be always a value (max, total, circulating) = 8,999,999,999