* Handle subdirectories without rx permission correctly
Allow ogg files w/o metadata, having taglib behave more like ffmpeg
* Fix test for walk_dir_tree, fix full reading of files in permission-
constrained directories, allow directories with leading ellipses
* Sorted directory traversal is preferred, and cleanup tests
* Small refactoring to clean-up `loadDir` function and to remove some "warnings" from IntelliJ
Co-authored-by: Deluan <deluan@navidrome.org>
This implements basic tests for functionality related to loading and
processing external album covers, both on the scanning size, and on the
display side.