[TASK] Add rescue tokens functionality to the handlers/bridge system

[drewstone]

Overview

We want to "rescue tokens" by signature on the Substrate side which can come about using a handler or potentially not. This task should include investigate into the potential routes we can take given Substrate's capabilities.

Details

There is already a treasury account in protocol-substrate and the fees are being sent there:
https://github.com/webb-tools/protocol-substrate/blob/main/pallets/token-wrapper/src/lib.rs#L105
https://github.com/webb-tools/protocol-substrate/blob/main/pallets/token-wrapper/src/lib.rs#L291

So we don't need to implement a separate treasury pallet. What we can instead do is the following:

• Add a rescue_tokens function to the token-wrapper pallet. This function signature for rescue_tokens should look something like:

fn rescue_tokens(asset_id: T::asset_id, to: T::AccountId, amount_to_rescue: BalanceOf<T>, nonce: u32)

• Add an execute_rescue_tokens function to the token-wrapper-handler pallet.
• Test the execution of rescue_tokens via the signature-bridge.