Add a way to load the WAV files of the GTA3 radios

[hardBSDk]

Currently Godot can't natively load unimported WAV files, thus we need to use a script.

There's this project, but it and the Godot 4.x PR doesn't work.

[atirut-w]

Actually, you can do it manually if you know how to parse WAV files. You just have to set the correct encoding format, mix rate, stereo, etc. Just shove the audio samples into the data array.