Wayland message box: improve zenity argument handling

[marcin-serwin]

Description

When no extra buttons are passed to zenity with --question --switch arguments it fails to show anything, however, SDL3 still reports success. To handle this case, we pass an additional "OK" button.

The double quotes were passed literally to the zenity arguments which resulted in the message box displaying literal "" when no text was given. The empty string is more logical in this case, e.g., the empty title results in the message box having lesser height.

Existing Issue(s)