adding mebx sample file from m59330 contributed by Apple

[podborski]

No description provided.

[podborski]

The files from this section were cross checked by Unified Streaming and are moved into the "published" directory. It is recommended that the information from this section be made available to the public alongside the actual conformance files.

Once we the failed checks are resolved we can merge this one.

[cconcolato]

The build does not pass because some "example" boxes are not officially registered. We add "example" to the JSON and update the framework to ignore them.

[DenizUgur]

@podborski I've added example box support. Just put "example": true to the example boxes inside the extension file (_gpac.ext.json).