Secondary sort options in library

[KingWaffleIII]

Describe your suggested feature

The user should be able to use multiple sort options with priority. For example, I want to sort my manga library by the last read but then further sorted by unread count so I have the manga I'm reading with the least amount of unread chapters at the very top. This would also sort manga I haven't started yet by their unread count, below all my started manga so I can start the shortest ones. It should look like from top to bottom:

• manga I'm reading with few chapters unread
• manga I'm reading with a lot of chapters unread
• manga I haven't started with few chapters unread
• manga I haven't started with a lot of chapters unread In this example, last read holds the most priority, then unread count.

Other details

No response

Acknowledgements

• [X] I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open or closed issue.
• [X] I have written a short but informative title.
• [X] If this is an issue with an official extension, I should be opening an issue in the extensions repository.
• [X] I have updated the app to version 0.15.2.4.
• [X] I will fill out all of the requested information in this form.