Accomodate Updated BIP 78 Spec

[DanGould]

BIP 78 got some fixes merged this morning

• Keep input utxo data through input finalization
• Allow mixed inputs

We must adjust to keep up to date as well as encourage other implementations to update since these are basically a relaxing of the rules.

Implementations that need updates:

• [x] rust-payjoin #505
• [x] BTCPayServer
  • [x] https://github.com/btcpayserver/BTCPayServer.BIP78/pull/2
  • [x] https://github.com/btcpayserver/BTCPayServer.BIP78/pull/3
• [ ] BitMask
• [ ] BlueWallet https://github.com/BlueWallet/BlueWallet/issues/7496
  • [ ] Tracking in the payjoin-client library: https://github.com/bitcoinjs/payjoin-client/pull/9
• [ ] Bull Bitcoin Mobile
• [ ] JoinMarket https://github.com/JoinMarket-Org/joinmarket-clientserver/issues/1761
• [ ] Nolooking (or archive)
• [x] Mutiny (WONTFIX because the repo is archived)
• [ ] Sparrow
  • [ ] Allow mixed input scripts
  • [x] Allow UTXO fields to be filled in
• [ ] Wasabi https://github.com/WalletWasabi/WalletWasabi/issues/13652

[DanGould]

Marked as "good first issue" regarding notifying and updating other BIP 78 implementations