Make track update asynchronous

[joeyy-watts]

Currently, every polling cycle, the script has to update the current playing track in a blocking operation, causing a slight but noticeable delay in the animation.

https://github.com/joeyy-watts/SpotifyWLED/blob/549e8102254d40f62234a9e76d519da1672ba85c/handlers/spotify_api_handler.py#L94

https://github.com/joeyy-watts/SpotifyWLED/blob/549e8102254d40f62234a9e76d519da1672ba85c/handlers/wled/wled_artnet.py#L32

This should be a non-blocking operation to allow animation to always run.

[joeyy-watts]

Using Threading to address this, but still have to refactor the code since update_current_track is not called in one place.

[joeyy-watts]

Addressed in:

• Add cache to get_cover https://github.com/joeyy-watts/SpotifyWLED/commit/2b216f7aaf5fc1a2fb9875a9ec93cdce5dcd2ad8
• Add cache to get_audio_feature https://github.com/joeyy-watts/SpotifyWLED/commit/a2e20c39fecafb54e4fd68e8913449184305cebb
• Use Thread for update current track https://github.com/joeyy-watts/SpotifyWLED/commit/cabdabfc0a3abccab46e7499b96ce9808d8a2518

Lag is still there, but not really noticeable in WLED matrix IRL. Only slight lag visible if viewing the ArtNet monitor.

There is still major lag upon track change, but will address this in separate issue.