[feature]: Enhance lnd with custom channels on-chain functionality

[dstadulis]

Deliverables

• Co-op Channel closure
  • MVP: Add another output to co-op close into which tap proofs are committed
• Force Channel closure
  • More complex, dependent on recent lnd sweeper changes. Current functionality: a force closure will be initiated but the tapd logic is lacking
• Asses HTLC Sweeper logic augmentation

[dstadulis]

Feature Branches:
https://github.com/lightninglabs/taproot-assets/tree/custom-channels-poc-coop-close
https://github.com/lightningnetwork/lnd/tree/custom-channels-poc-coop-close

[dstadulis]

With #970 merged, the necessary support from tapd was added to transfer -- and arbitrate HTLC settlement -- of taproot assets over the lightning network.

Code integration point lightninglabs/lightning-terminal#782