Custom Transactions Tracking Issue

[tankyleo]

PR to review: #3606

Custom Commitment and HTLC Transactions

Build

• Add TxBuilder::build_commitment_transaction: [Custom Transactions] Define the TxBuilder trait #3606

Validate

• Move all holder commitment validation in FundedChannel to XX::validate_holder_commitment

Claims Detection

• Refactor ChannelMonitor
• Add generate_claims_from_holder_tx
• Add generate_claims_from_counterparty_tx
• Add generate_claims_from_revoked_counterparty_tx

Claims Spend

• Transition from {Ecdsa, Taproot}ChannelSigner methods returning a Signature to ChannelSigner methods returning a Witness
  • sign_holder_commitment
  • sign_justice_revoked_output
  • sign_justice_revoked_htlc_output
  • sign_holder_htlc_transaction
  • sign_counterparty_htlc_transaction
  • sign_holder_anchor_input
• Create a single call "Alice: here's a claim, and a transaction I am building to claim it, Bob: Here's the witness"

Custom Funding Output and Mutual Close Transaction

Build Funding Output

• Add get_funding_script_pubkey

Validate Witness Data Provided By Counterparty

• Move all validation of the counterparty's mutual close partial witness from FundedChannel to XX::validate_closing_partial_witness
  • A partial witness is a full ecdsa signature for ecdsa channels, and a partial sig, nonce pair in musig2 channels.

Build Mutual Close Transaction

• Add build_final_closing_transaction

Prior Work

• Let ChannelSigner set and spend LN scriptpubkeys #3512