macosx: Improve responsiveness of initial load of audio library
Mostly achieved by asynchronously fetching data on background threads, alleviating UI freezing
After fix:
Screen_Recording_2023-04-17_at_18.44.15
Before fix:
Screen_Recording_2023-04-17_at_18.41.03
Signed-off-by: Claudio Cambra developer@claudiocambra.com