Sort token pairs list by decreasing TVL

[dib542]

The endpoint /liquidity/pairs of the indexer currently (from #36) returns an unsorted list of token pairs, but by looking up the chain-registry Asset for each token and then querying CoinGecko, we can determine the TVL of each pair and sort them correctly in descending order.

The "looking up chain registry assets" comes with several levels of "freshness":

• use the npm chain-registry package
  • has all current registered main and testnet asset, chain, and IBC info
  • gets out of date quickly: as soon as a new asset or IBC channel is registered
• use npm @chain-registry/client package (and chain-registry package and live chain queries)
  • can download new assets, chains, and IBC info dynamically
  • requires a list of chain names so that it can download just the relevant chain, chain-assets, and IBC connection JSONs
  • relevant chain names can be found by querying the live chain and looking up chain_id in chain of chain-registry
  • gets out of date less quickly: but will still fail to detect newly registered chains after chain-registry was installed

Either could be used, but it seems like the extra dynamic fetching of assets may not be worth the trouble because it doesn't solve the issue of how to identify assets of newly registered chains. And either of these solutions should work well if we can first resolve:

• 39

[dib542]

The first level of this has been attempted with #40