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/channel_reestablish.go

@@ -82,8 +82,7 @@ type ChannelReestablish struct {
 	// This will only be populated if the simple taproot channels type was
 	// negotiated.
 	//
-	// TODO(roasbeef): rename to verification nonce
-	LocalNonce *Musig2Nonce
+	LocalNonce OptMusig2NonceTLV
 
 	// DynHeight is an optional field that stores the dynamic commitment
 	// negotiation height that is incremented upon successful completion of
@@ -138,9 +137,9 @@ func (a *ChannelReestablish) Encode(w *bytes.Buffer, pver uint32) error {
 	}
 
 	recordProducers := make([]tlv.RecordProducer, 0, 1)
-	if a.LocalNonce != nil {
-		recordProducers = append(recordProducers, a.LocalNonce)
-	}
+	a.LocalNonce.WhenSome(func(localNonce Musig2NonceTLV) {
+		recordProducers = append(recordProducers, &localNonce)
+	})
 	a.DynHeight.WhenSome(func(h DynHeight) {
 		recordProducers = append(recordProducers, &h)
 	})
@@ -203,8 +202,10 @@ func (a *ChannelReestablish) Decode(r io.Reader, pver uint32) error {
 		return err
 	}
 
-	var localNonce Musig2Nonce
-	var dynHeight DynHeight
+	var (
+		dynHeight  DynHeight
+		localNonce = a.LocalNonce.Zero()
+	)
 	typeMap, err := tlvRecords.ExtractRecords(
 		&localNonce, &dynHeight,
 	)
@@ -212,8 +213,8 @@ func (a *ChannelReestablish) Decode(r io.Reader, pver uint32) error {
 		return err
 	}
 
-	if val, ok := typeMap[NonceRecordType]; ok && val == nil {
-		a.LocalNonce = &localNonce
+	if val, ok := typeMap[a.LocalNonce.TlvType()]; ok && val == nil {
+		a.LocalNonce = tlv.SomeRecordT(localNonce)
 	}
 	if val, ok := typeMap[CRDynHeight]; ok && val == nil {
 		a.DynHeight = fn.Some(dynHeight)