Clean up manga restoring logic

Some behavior changes:
- It prioritizes new entries, then anything more recently updated
- It copies the more recently updated entry's metadata (description, thumbnail, etc.)

data/src/main/sqldelight/tachiyomi/data/mangas.sq

@@ -70,6 +70,10 @@ getAllManga:
 SELECT *
 FROM mangas;
 
+getAllMangaSourceAndUrl:
+SELECT source, url
+FROM mangas;
+
 getMangasWithFavoriteTimestamp:
 SELECT *
 FROM mangas