Add option to download selected chapters only (to avoid large downloads)

[wxuan1990]

Currently, the Android app seems to download all chapters at once when initiating a download. For audiobooks with many chapters, this can result in very large file sizes (sometimes over 10GB), which may not be desirable or practical for users with limited storage or data plans.

It would be great if the app could offer an option to download only specific chapters , rather than downloading everything automatically. This would allow users to manage their storage more efficiently and choose what they need to listen to offline.

[nichwall]

advplyr/audiobookshelf-app#1431