Fix ProtocolGame::sendModalWindow

[EPuncker]

Pull Request Prelude

• I have followed proper The Forgotten Server code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

Fix sendModalWindow for QT clients because they have swapped default button bytes

How to reproduce:

1. go to a bed at any house and use it
2. modal window will open
3. press "enter" at your keyboard

expected: execution of the selected menu option

what happen instead: action canceled, window closed

and if you do the steps above and press "esc" instead, it will execute the action...