feature: `registry` fetch asset information from chain registry

Related to: #157

## Overview
Currently assets are not properly structured, and are incorrect. `registry` service should be able to fetch `assetList` of a denom from `base` and populate itself.

## Proposal
1. Fetch infomation directly from chain registry via call to github chain-registry
2. Use a go client, which already has chain information baked in. Similar to the npm package of `chain-registry`
3. Mention information in `default.yaml`

## Default
If the chain or denom does not exist on chain-registry, we keep using the current default asset.