The `TxBuilder` is now created from the `build_tx` or `build_fee_bump` functions on wallet and the
final transaction is created by calling `finish` on the builder.
-- Removed `TxBuilder::utxos` in favor of repeatedly calling `add_utxo`
+- Removed `TxBuilder::utxos` in favor of `TxBuilder::add_utxos`
- Added `Wallet::build_tx` to replace `Wallet::create_tx`
- Added `Wallet::build_fee_bump` to replace `Wallet::bump_fee`
- Added `Wallet::get_utxo`