Save Spotify album_id and track_id as flexible attributes

[arsaboo]

Description

Partially Fixes #4347.

Added additional keys to save Spotify track_id and album_id as flexible attributes.

To Do

• Documentation. (If you've add a new command-line flag, for example, find the appropriate page under docs/ to describe it.)
• Changelog. (Add an entry to docs/changelog.rst near the top of the document.)
• Tests. (Encouraged but not strictly required.)

[sampsyo]

Cool!! Thanks for getting this started! Have you had a chance to try it out? Does it work as expected?

If it does, a next step would be to craft a quick changelog entry describing the new feature.

[arsaboo]

Yes, it does. Here's the output of the item_attributes table that has all the information.

[sampsyo]

Awesome; thanks for adding this! Seems like a good first step!