Update ex-opus-multichannel hoa-player with drag and drop to Main branche

Hi
May I request that the hoa-player example in branch exp-opus-multichannel be modified and added in main branch.

Suggestions for improvements
- Allow selection of files from resources directory for playback in addition to Drag and Drop Selection.
- Create a drop down menu to allow selection files in resources to be chosen for playback.
- allow resources to to contain single files with 16 channel TOA compressed files, for example Opus files.
- allow selection of FOA or HOA renderer during playback.

Best Regards
Bo-Erik Sandholm