* Reencode mp3 sounds at lower bitrate, mono.
* Encode wav sounds as mp3.
* Remove unused sound file.
* Add opus encoded sounds.
* Add a script to encode sounds.

Co-authored-by: DimaG <dgeorgiev06@gmail.com>

On Android the files will be copied to the assets/sounds directory of
the SDK bundle on build time. To play the "asset:/" prefix has to be
used to locate the files correctly.

On iOS each sound file must be added to the SDK's Xcode project in order
to be bundled correctly. To playback we need to know the path of the SDK
bundle which is now exposed by the AppInfo iOS module.