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/chanfunding/coin_select.go

@@ -219,7 +219,7 @@ func CoinSelectSubtractFees(feeRate chainfee.SatPerKWeight, amt,
 
 	// If the the output is too small after subtracting the fee, the coin
 	// selection cannot be performed with an amount this small.
-	if outputAmt <= dustLimit {
+	if outputAmt < dustLimit {
 		return nil, 0, 0, fmt.Errorf("output amount(%v) after "+
 			"subtracting fees(%v) below dust limit(%v)", outputAmt,
 			requiredFeeNoChange, dustLimit)
@@ -233,7 +233,7 @@ func CoinSelectSubtractFees(feeRate chainfee.SatPerKWeight, amt,
 	// If adding a change output leads to both outputs being above
 	// the dust limit, we'll add the change output. Otherwise we'll
 	// go with the no change tx we originally found.
-	if newChange > dustLimit && newOutput > dustLimit {
+	if newChange >= dustLimit && newOutput >= dustLimit {
 		outputAmt = newOutput
 		changeAmt = newChange
 	}