Add slippage on swap configurations

[luizstacio]

We should be able to set a slippage % to the transaction, this enables the user to have better visibility on the swap and avoid issues due to changes in reserves during the swap process.

When swapping with minimum

• Slippage is calculated over the value to be sent, ex; swap_with_maximum(amount * (1 - slippage), ....)
  • This would result in reducing the minimum amount expected from the swap by calculating
    When swapping with maximum
• Slippage is calculated over the value to be sent, ex;

    swap_with_maximum(amount, DEADLINE, ....,{
      forward: [forwardAmount.amount * (1 + slippage), from],
      variableOutputs: 1,
    });

• In this case we would like to show the price before the transaction, it would be done on another issue;