GetFee's GetChain from msg.TargetAsset, not msg.Destination

Credit to Bas1c for finding that Address-received GetChain (used for handler_swap.go GetFee) cannot distinguish between ETHChain and AVAXChain,
as well as for the suggestion of using TargetAsset to determine chain instead.

common/address.go

@@ -227,6 +227,8 @@ func getBCHAddressV83(address bchutil.Address, cfg *bchchaincfg.Params) (Address
 	return NoAddress, fmt.Errorf("invalid address type")
 }
 
+// Avoid using this except for network (e.g. mainnet/testnet) determination,
+// as it currently cannot determine whether chain is ETHChain or AVAXChain by address.
 func (addr Address) IsChain(chain Chain) bool {
 	if chain.IsEVM() {
 		return strings.HasPrefix(addr.String(), "0x")
@@ -317,6 +319,8 @@ func (addr Address) IsChain(chain Chain) bool {
 	}
 }
 
+// Avoid using this except for network (e.g. mainnet/testnet) determination,
+// as it currently cannot determine whether chain is ETHChain or AVAXChain by address.
 func (addr Address) GetChain() Chain {
 	for _, chain := range []Chain{ETHChain, BNBChain, THORChain, BTCChain, LTCChain, BCHChain, DOGEChain, TERRAChain, GAIAChain, AVAXChain} {
 		if addr.IsChain(chain) {