When fetching chain from chain-registry, gas-prices are calculated incorrectly

[freak12techno]

So I initialized a new config and added Sentinel chain by doing this:

rly chains add sentinel

It generated a config with the following gas prices:

            gas-prices: 0.01udvpn

although on Sentinel, the correct minimal-gas-price is 0.1udvpn.

Looking at the code, I see it's being generated here:

relayer/cregistry/chain_info.go

Line 302 in 4e4e953

gasPrices = fmt.Sprintf("%.2f%s", 0.01, assetList.Assets[0].Base)

, and it has two issues:

1. it just takes the first denom from the assetlist, which might be incorrect
2. it assumes that for all chains, the minimal-gas-price is 0.01 of this denom, which also may be wrong.

I think the more correct approach would be to take it from the fee_tokens of the chain itself, like here on Sentinel: https://github.com/cosmos/chain-registry/blob/master/sentinel/chain.json#L17