* added duplicate manga check
When adding a manga to your library, the app will go through each manga previously added and compare their names. If a match is detected, it will prompt the user and ask for confirmation. On this prompt there is also an option to view the other manga.
* added german translations for newly added strings
* Revert "added german translations for newly added strings"
This reverts commit 71ada62067.
* changed `AlertDialog.Builder` to `MaterialAlertDialogBuilder`
* using SQL query instead of filtering entire library with Kotlin
<stringname="confirm_manga_add_duplicate">You have an entry in your library with the same name but from a different source (%1$s).\n\nDo you still wish to continue?</string>
<stringname="manga_added_library">Added to library</string>
<stringname="manga_removed_library">Removed from library</string>