FEATURE: Improve playback support

[Arkshine]

This PR improves playback compatibility by relying on a third-party library and, most importantly, converting the output to MP3. The library uses AudioContext API, so the output can be processed to MP3 using a web worker.

The changes are pretty straightforward.
It fixes two minor issues as well:

• The audio length would not change after the first recording (missing @tracked on _audioData)
• Make sure to clean any recording if the modal is closed

Added a few tests:

Note: The user needs to allow the mp3 extension in authorized_extensions or authorized extensions_staff settings.

[angusmcleod]

@Arkshine Great work!

[Arkshine]

Thanks for giving me feedback; I appreciate it!