feat: ADR-009: Supply module

[leobragaz]

Description

Closes: #773 .

This PR implements the x/supply module which serves some useful APIs to query both TotalSupply (converted from millionth) and CirculatingSupply.

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[codecov]

Codecov Report

Merging #782 (90f8ec4) into master (b358016) will increase coverage by 0.01%.
The diff coverage is 82.79%.

❗ Current head 90f8ec4 differs from pull request most recent head df47a9f. Consider uploading reports for the commit df47a9f to get more accurate results

@@            Coverage Diff             @@
##           master     #782      +/-   ##
==========================================
+ Coverage   81.39%   81.41%   +0.01%     
==========================================
  Files          78       81       +3     
  Lines        6747     6839      +92     
==========================================
+ Hits         5492     5568      +76     
- Misses       1001     1013      +12     
- Partials      254      258       +4     

Impacted Files	Coverage Δ
x/supply/keeper/querier.go	60.00% <60.00%> (ø)
x/supply/keeper/keeper.go	95.12% <95.12%> (ø)
app/app.go	82.47% <100.00%> (+0.23%)	⬆️
x/supply/keeper/grpc_query.go	100.00% <100.00%> (ø)

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[dadamu]

Looks good to me

[RiccardoM]

Instead of returning a QueryTotalSupplyResponse, is there any way we can simply return a string here instead? So the REST response instead of looking like this

{
  "total_supply": "<amount>"
}

Can simply look like this:

"<amount>"

Maybe something like StringValue from wrappers.proto can work like this

[leobragaz]

Done, but that makes the Protobuf linter angry...any way to skip to kind of checks on query returns types? @RiccardoM

[leobragaz]

[leobragaz]

The result isn't what expected btw. Should we roll-back to the previous one?

[RiccardoM]

Considering CoinMarketCap requires the supply value to be returned simply as a value, we need a way to have this as well. From their docs we can read:

API endpoint that displays ONLY 'Total Supply' as a numerical value (e.g. http://chainz.cryptoid.info/grs/api.dws?q=totalcoins)

Probably the best way would be to register a custom REST endpoint. This can be done using the RegisterRESTRoutes module method and registering a custom endpoint there.

Once that's done, we can simply revert to the previous answers for the gRPC endpoints

[leobragaz]

Both done 👍