Add a button to generate a cover for any book

[Aitanuqui]

📝 Description

Extend #1438 by adding a button to generate a cover for any book, regardless of format.

🌟 Benefits

• Makes libraries visually consistent and appealing.
• Saves users time finding or designing covers.
• Helps with identification and navigation of books.

💻 Use Cases

1. Generate covers for books with missing covers in all formats.
2. Replace low-resolution or unattractive covers in a library.

📌 Additional Context

I stressed about formats because currently it only seems to apply to EPUBs with missing cover.