support Cantillon aggregate data for currencies

[brenzi]

like for Gesell, we'd like to show

• number of participants registered
• number of meetups assigned
• money supply
• ceremony reward (the nominal value of the UBI per ceremony)

this can be queried from the worker-api (which has already been implemented for our flutter app

The CLI client does it like this:
https://github.com/encointer/encointer-worker/blob/53e9ef984086824c8b867b06cc6c5c3675011779/stf/src/cli.rs#L211-L275

and returns:

> nctr trusted info -m $MRENCLAVE --shard $cid
Public information about currency HKKAHQhLbLy8b84u1UjnHX9Pqk4FXebzKgtqSt8EKsES
  total issuance: 0
  participant count: undisclosed (might be REGISTERING phase?)
  meetup count: 0
  ceremony reward: 1
  location tolerance: 1000m
  time tolerance: 600000ms

during registering phase, or

> nctr trusted info -m $MRENCLAVE --shard $cid
Public information about currency HKKAHQhLbLy8b84u1UjnHX9Pqk4FXebzKgtqSt8EKsES
  total issuance: 0
  participant count: 3
  meetup count: 1
  ceremony reward: 1
  location tolerance: 1000m
  time tolerance: 600000m

during other phases

[brenzi]

Caveat: Cantillon works differently than Gesell. The Scheduler and Currencies pallets work the same, but the Ceremonies and Balances pallets moved into SubstraTEE-worker enclave and can't be queried via chain RPC. We need to use worker-api instead.

Anyway, we could still show the map with locations, but no data on money supply or activity

More spec to come

[brenzi]

The on-chain basics work out of the box:

https://explorer.encointer.org/?rpc=wss://cantillon.encointer.org

But no info on worker state.

[brenzi]

Since worker v0.6.9 we can query all the necessary information for the explorer from the worker-api. See rust code how this works:
https://github.com/encointer/encointer-worker/blob/53e9ef984086824c8b867b06cc6c5c3675011779/stf/src/cli.rs#L211-L275

[brenzi]

@clangenb has implemented all worker-api's in encointer wallet app in js:
https://github.com/encointer/encointer-wallet-flutter/blob/master/lib/js_service_encointer/src/service/worker.js

These functions should be moved to our npm package for better reusability and maintenance:
https://github.com/encointer/encointer-js