refactor: improve banking money handling to prevent potential exploit

[AlexRXWindy]

Description

This PR refactors and improves the money-handling logic within the ESX Banking system.
The refactor enhances both security and stability while maintaining backward compatibility with existing ESX Banking functionality.

[CLAassistant]

All committers have signed the CLA.

[simpleC0de]

Hey @AlexRXWindy , thanks for the PR! The idea of adding rollback logic is good, but there's a critical issue:

ESX's addAccountMoney() and removeAccountMoney() don't return boolean values - they return nil. This means your checks
like if xPlayer.removeAccountMoney('bank', amount) then will always evaluate to false, breaking all banking operations.

Suggested fix: Check balance before operations instead:

  Withdraw = function(amount, xPlayer)
      if xPlayer.getAccount('bank').money < amount then return false end
      xPlayer.removeAccountMoney('bank', amount)
      xPlayer.addAccountMoney('money', amount)
      return true
  end

Also minor: please use xPlayer.source consistently (not xPlayer.src).

[simpleC0de]

See comment above - the ESX functions don't return booleans