Custom Feehandler & Add destination to FeeReason

[yrong]

Context

Explore the idea from Alistair

1. The exporter adds the teleported dot to the cost and returns it. This will make sure the user is charged the full amount.
2. In a custom fee handler the Ethereum location must not be waived.
3. In a custom fee handler we check if the the destination is Ethereum(our bridge) then we transfer to the treasury the cost - teleported dot. i.e. burning teleported dot

and solve the issue

The challenge here is that in FeeHandler here, there is no context of the original destination(i.e. Ethereum). So seems not possible to do the hack above?

with destination(i.e. Ethereum) added into the FeeReason of InitiateReserveWithdraw.