Automate fee rate calculation

[dangershony]

Bringing this back to life we now have the fee endpoint It would be nice to have a sliding option to select fee rate

https://btc.indexer.angor.io/api/stats/fee?confirmations=1&confirmations=5&confirmations=10

example response.

{"fees":[{"confirmations":1,"feeRate":28218},{"confirmations":5,"feeRate":21033},{"confirmations":10,"feeRate":10048}]}