📝 andremralves opened a pull request: "Add and use `satToBtc` and `btcToSat` util functions"
(https://github.com/bitcoin/bitcoin/pull/31356)
Introduce utility functions `satToBtc` and `btcToSat` to simplify and standardize conversions between satoshis and bitcoins in functional tests

#closes #31345

## Number of updates
```bash
➜ bitcoin git:(btc-to-sat) ✗ git grep -n "satToBtc(" -- '*.py' | wc -l
22
➜ bitcoin git:(btc-to-sat) ✗ git grep -n "btcToSat(" -- '*.py' | wc -l
152
```

<details>
<summary>Satoshis to BTC conversion instances</summary>

```bash
test/functional/feature_fee_estimation.py:130: fee_rate=
...