Add UTXO selection sort option #16
Description
Should be possible to sort how UTXOs are picked from the wallet, based at least on the following criteria:
- UTXO age (ascending / descending)
- UTXO size (ascending / descending)
These should allow users to have the wallet automatically select or even pre-select UTXOs (combined with manual #15 task, so that user don't need to do manual task.