multi: upgrade new taproot TLVs to use tlv.OptionalRecordT

In this commit, we update new Taproot related TLVs (nonces, partial sig,
sig with nonce, etc). Along the way we were able to get rid of some
boiler plate, but most importantly, we're able to better protect against
API misuse (using a nonce that isn't initialized, etc) with the new
options API. In some areas this introduces a bit of extra boiler plate,
and where applicable I used some new helper functions to help cut down
on the noise.

Note to reviewers: this is done as a single commit, as changing the API
breaks all callers, so if we want things to compile it needs to be in a
wumbo commit.

lnwire/partial_sig.go

@@ -11,11 +11,20 @@ import (
 const (
 	// PartialSigLen is the length of a musig2 partial signature.
 	PartialSigLen = 32
+)
 
-	// PartialSigRecordType is the type of the tlv record for a musig2
+type (
+	// PartialSigType is the type of the tlv record for a musig2
 	// partial signature. This is an _even_ type, which means it's required
 	// if included.
-	PartialSigRecordType tlv.Type = 6
+	PartialSigType = tlv.TlvType6
+
+	// PartialSigTLV is a tlv record for a musig2 partial signature.
+	PartialSigTLV = tlv.RecordT[PartialSigType, PartialSig]
+
+	// OptPartialSigTLV is a tlv record for a musig2 partial signature.
+	// This is an optional record type.
+	OptPartialSigTLV = tlv.OptionalRecordT[PartialSigType, PartialSig]
 )
 
 // PartialSig is the base partial sig type. This only encodes the 32-byte
@@ -36,7 +45,7 @@ func NewPartialSig(sig btcec.ModNScalar) PartialSig {
 // Record returns the tlv record for the partial sig.
 func (p *PartialSig) Record() tlv.Record {
 	return tlv.MakeStaticRecord(
-		PartialSigRecordType, p, PartialSigLen,
+		(PartialSigType)(nil).TypeVal(), p, PartialSigLen,
 		partialSigTypeEncoder, partialSigTypeDecoder,
 	)
 }
@@ -88,16 +97,35 @@ func (p *PartialSig) Decode(r io.Reader) error {
 	return partialSigTypeDecoder(r, p, nil, PartialSigLen)
 }
 
+// SomePartialSig is a helper function that returns an otional PartialSig.
+func SomePartialSig(sig PartialSig) OptPartialSigTLV {
+	return tlv.SomeRecordT(tlv.NewRecordT[PartialSigType, PartialSig](sig))
+}
+
 const (
 	// PartialSigWithNonceLen is the length of a serialized
 	// PartialSigWithNonce. The sig is encoded as the 32 byte S value
 	// followed by the 66 nonce value.
 	PartialSigWithNonceLen = 98
+)
 
-	// PartialSigWithNonceRecordType is the type of the tlv record for a
-	// musig2 partial signature with nonce. This is an _even_ type, which
-	// means it's required if included.
-	PartialSigWithNonceRecordType tlv.Type = 2
+type (
+	// PartialSigWithNonceType is the type of the tlv record for a musig2
+	// partial signature with nonce. This is an _even_ type, which means
+	// it's required if included.
+	PartialSigWithNonceType = tlv.TlvType2
+
+	// PartialSigWithNonceTLV is a tlv record for a musig2 partial
+	// signature.
+	PartialSigWithNonceTLV = tlv.RecordT[
+		PartialSigWithNonceType, PartialSigWithNonce,
+	]
+
+	// OptPartialSigWithNonceTLV is a tlv record for a musig2 partial
+	// signature.  This is an optional record type.
+	OptPartialSigWithNonceTLV = tlv.OptionalRecordT[
+		PartialSigWithNonceType, PartialSigWithNonce,
+	]
 )
 
 // PartialSigWithNonce is a partial signature with the nonce that was used to
@@ -129,8 +157,9 @@ func NewPartialSigWithNonce(nonce [musig2.PubNonceSize]byte,
 // Record returns the tlv record for the partial sig with nonce.
 func (p *PartialSigWithNonce) Record() tlv.Record {
 	return tlv.MakeStaticRecord(
-		PartialSigWithNonceRecordType, p, PartialSigWithNonceLen,
-		partialSigWithNonceTypeEncoder, partialSigWithNonceTypeDecoder,
+		(PartialSigWithNonceType)(nil).TypeVal(), p,
+		PartialSigWithNonceLen, partialSigWithNonceTypeEncoder,
+		partialSigWithNonceTypeDecoder,
 	)
 }
 
@@ -199,3 +228,20 @@ func (p *PartialSigWithNonce) Decode(r io.Reader) error {
 		r, p, nil, PartialSigWithNonceLen,
 	)
 }
+
+// MaybePartialSigWithNonce is a helper function that returns an optional
+// PartialSigWithNonceTLV.
+func MaybePartialSigWithNonce(sig *PartialSigWithNonce,
+) OptPartialSigWithNonceTLV {
+
+	if sig == nil {
+		var none OptPartialSigWithNonceTLV
+		return none
+	}
+
+	return tlv.SomeRecordT(
+		tlv.NewRecordT[PartialSigWithNonceType, PartialSigWithNonce](
+			*sig,
+		),
+	)
+}