multi: add version to MuSig2 API, bump btcd/btcec to v2.3.2

With this commit we bump the github.com/btcd/btcec/v2 library to v2.3.2
which implements the MuSig2 BIP version v1.0.0rc2. With this the
github.com/btcsuite/btcd/btcec/v2/schnorr/musig2 package becomes
v1.0.0rc2 and the github.com/lightningnetwork/lnd/internal/musig2v040
stays at the old v0.4.0 version.

lnwallet/rpcwallet/rpcwallet.go

@@ -640,8 +640,9 @@ func (r *RPCKeyRing) ComputeInputScript(tx *wire.MsgTx,
 // all signing parties must be provided, including the public key of the local
 // signing key. If nonces of other parties are already known, they can be
 // submitted as well to reduce the number of method calls necessary later on.
-func (r *RPCKeyRing) MuSig2CreateSession(keyLoc keychain.KeyLocator,
-	pubKeys []*btcec.PublicKey, tweaks *input.MuSig2Tweaks,
+func (r *RPCKeyRing) MuSig2CreateSession(bipVersion input.MuSig2Version,
+	keyLoc keychain.KeyLocator, pubKeys []*btcec.PublicKey,
+	tweaks *input.MuSig2Tweaks,
 	otherNonces [][musig2.PubNonceSize]byte) (*input.MuSig2SessionInfo,
 	error) {
 
@@ -690,6 +691,7 @@ func (r *RPCKeyRing) MuSig2CreateSession(keyLoc keychain.KeyLocator,
 
 	// De-Serialize all the info back into our native struct.
 	info := &input.MuSig2SessionInfo{
+		Version:       bipVersion,
 		TaprootTweak:  tweaks.HasTaprootTweak(),
 		HaveAllNonces: resp.HaveAllNonces,
 	}