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.)

(cherry picked from commit 58daedc89ee18d04e7af5bab12629680dba4096c)

# Conflicts:
#	app/src/main/java/eu/kanade/tachiyomi/data/backup/BackupRestorer.kt
#	app/src/main/java/eu/kanade/tachiyomi/source/model/SMangaExtensions.kt

domain/src/main/java/tachiyomi/domain/manga/interactor/GetMangaByUrlAndSourceId.kt

@@ -6,7 +6,7 @@ import tachiyomi.domain.manga.repository.MangaRepository
 class GetMangaByUrlAndSourceId(
     private val mangaRepository: MangaRepository,
 ) {
-    suspend fun awaitManga(url: String, sourceId: Long): Manga? {
+    suspend fun await(url: String, sourceId: Long): Manga? {
         return mangaRepository.getMangaByUrlAndSourceId(url, sourceId)
     }
 }