* Rename "DownloadedFilesProvider" to "ChaptersFilesProvider"
* Move files into sub packages
* Further abstract "DownloadedFilesProvider"
* Rename "getCachedImageResponse" to "getImageResponse"
* Extract getting cached image response into new function
* Decouple thumbnail cache and download
* Download and delete permanent thumbnails
When adding/removing manga from/to the library make sure the permanent thumbnail files will get handled properly
* Move thumbnail cache to actual temp folder
* Rename "mangaDownloadsRoot" to "downloadRoot"
* Move manga downloads into "mangas" subfolder
* Clear downloaded thumbnail
