Support Kobo audiobooks

[cerdelyan]

Support Kobo audiobooks; separated from #23

Supporting alternate marketplaces will make it easier for people to see their libraries all in one place. This would save time and prevent duplicate purchases. If there are multiple copies present, marketplace indicators could overlap or include multiple tags.

I'm not sure if there's a repo that supports Kobo audiobooks. I believe there was an ebook repo that was able to handle the audiobooks but it was an addition not as well supported.

[cerdelyan]

This might have been the one: https://github.com/subdavis/kobo-book-downloader

https://github.com/PrimalZed/kobo-book-downloader-vue

https://www.reddit.com/r/audiobooks/comments/c3bqkq/comment/js08amr/