Add basic APOD routs

[GNMoseke]

Adds routes for:

• Downloading/Storing NASA APOD along with creating a mongo entry referencing it
• Marking an APOD as a favorite

Fixes:

• Fixed backlog retrieval not working when providing a filter type/value match taht contained a non-string value (e.g. favorite or rating)

Misc

• Documentation cleanup
• Adds cargo clippy github action