multi: replace DefaultDustLimit with script-specific DustLimitForSize

This commit updates call-sites to use the proper dust limits for
various script types. This also updates the default dust limit used
in the funding flow to be 354 satoshis instead of 573 satoshis.

lnwallet/wallet.go

@@ -689,12 +689,15 @@ func (l *LightningWallet) handleFundingReserveRequest(req *InitFundingReserveMsg
 	// If no chanFunder was provided, then we'll assume the default
 	// assembler, which is backed by the wallet's internal coin selection.
 	if req.ChanFunder == nil {
+		// We use the P2WSH dust limit since it is larger than the
+		// P2WPKH dust limit and to avoid threading through two
+		// different dust limits.
 		cfg := chanfunding.WalletConfig{
 			CoinSource:       &CoinSource{l},
 			CoinSelectLocker: l,
 			CoinLocker:       l,
 			Signer:           l.Cfg.Signer,
-			DustLimit:        DefaultDustLimit(),
+			DustLimit:        DustLimitForSize(input.P2WSHSize),
 		}
 		req.ChanFunder = chanfunding.NewWalletAssembler(cfg)
 	}