lnwallet/chanfunding: update assemblers to support musig2

In this commit, we update the set of intents and assemblers to recognize
musig2. For this change, we use a new bool, `musig2`, then use that to
determine if we need to use the new taproot funding scripts or not.

lnwallet/chanfunding/wallet_assembler.go

@@ -476,6 +476,7 @@ func (w *WalletAssembler) ProvisionChannel(r *Request) (Intent, error) {
 			ShimIntent: ShimIntent{
 				localFundingAmt:  localContributionAmt,
 				remoteFundingAmt: r.RemoteAmt,
+				musig2:           r.Musig2,
 			},
 			InputCoins: selectedCoins,
 			coinLocker: w.cfg.CoinLocker,