[CONTRACT] Implement relaying service

[1Mateus]

Implement a gas-station to pay for gas for all withdrawals.

This is deployed as a module on chain.

Refer to this sample implementation:

https://docs.kadena.io/build/guides/building-a-voting-dapp#implementing-the-gas-station

The relaying service must:

pay for gas only for transactions that withdraw from the contract

charge a fee in the tokens being withdrawn that is greater than the cost of relaying the transaction

[veigajoao]

https://github.com/kadena-io/memory-wall/tree/master