Improve gas fee calculation when missing estimations

[euharrison]

In case the indexer do have estimations, we apply our math and it works fine

But in case the indexer don't have estimations (totalEstimations:0), it returns the default value, and, when we apply the math, it scales more on top of it

Example:

• (estimates) 1 bond = https://namada-idx.emberstake.xyz/api/v1/gas/estimate?bond=1

{
  "min": 22315,
  "max": 25090,
  "avg": 23408,
  "totalEstimates": 20
}

• (without estimates) 2 bonds = https://namada-idx.emberstake.xyz/api/v1/gas/estimate?bond=2

{
  "min": 100000,
  "max": 100000,
  "avg": 100000,
  "totalEstimates": 0
}

What we can do on Namadillo is apply a different scale factor based on the totalEstimates

[neocybereth]

Here's a separate todo on this that may be worth doing at the same time