coin metadata config for nhash

[iramiller]

Create a coin denom metadata configuration for hash that maps nhash and hash as 1x10^8 nhash, etc. For examples of how the bank module handles denom metadata refer to: https://github.com/cosmos/cosmos-sdk/blob/master/x/bank/types/metadata_test.go

[iramiller]

We might actually want to put this in the chain somehow ... even if it is just in the local testnets for now. It would be good info for @crussell-figure to refer to for the Explorer project.

{
  "description": "The native staking token of the Provenance Blockchain.",
  "denom_units": [
    {
      "denom": "nhash",
      "exponent": 0,
      "aliases": [
        "nanohash"
      ],
    },
    {
      "denom": "hash",
      "exponent": 9,
    }
  ],
  "base": "nhash",
  "display": "hash",
}

provenanced q bank denom-metadata

I believe the denom metadata endpoints are not currently wired into the rest services in 0.41 of the sdk.

[iramiller]

This is related to #47. It would probably be best to use the Marker Module endpoints for display/setting of denom metadata for integration with the explorer "Asset" pages.