Make Spotify API calls asynchronous.

[a-rich]

Is your feature request related to a problem? Please describe.
Spotify API calls should be made asynchronously via a package like tekore

Describe the solution you'd like

• ThreadPoolExecutor usage should be replaced with asynchronous calls to Spotify API.
• Spotify API calls are rate-limited so a class for queuing requests and responding to 429 response status codes by throttling requests and pushing failed requests to the head of the queue must be implemented.
• The possibility of batch search API requests should also be investigated.