Support for sidecar covers in WEBP format

[PhilippKammann]

Describe your suggested feature

Similiar how you can add a cover.png or cover.jpg to a series folder to set a poster for the series, it would be nice if cover.webp would be supported as well.

In the same vein, support for book 123.webp to set a poster for a book through a sidecar file.

Other details

No response

Acknowledgements

• I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open issue.
• I have written a short but informative title.
• I have updated the app to the latest version.
• I will fill out all of the requested information in this form.

[gotson]

🎉 This issue has been resolved in v1.5.0 (Release Notes)