Tweak flag classes for Library (#7829)

* Tweak flag classes for Library

- Add interface for Flag and Mask
- Merge Sort Type and Direction into one class
- Use custom serializers for preferences
  - Mainly to not break the old

* Review changes

(cherry picked from commit 880407442c)

# Conflicts:
#	app/build.gradle.kts
#	app/src/main/java/eu/kanade/domain/category/interactor/SetDisplayModeForCategory.kt
#	app/src/main/java/eu/kanade/domain/category/interactor/SetSortModeForCategory.kt
#	app/src/main/java/eu/kanade/tachiyomi/data/preference/PreferencesHelper.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/browse/BrowseSourceController.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/browse/SourceItem.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryPresenter.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/library/LibrarySettingsSheet.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/library/setting/SortDirectionSetting.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/library/setting/SortModeSetting.kt

app/src/main/java/eu/kanade/data/category/CategoryRepositoryImpl.kt

@@ -11,6 +11,10 @@ class CategoryRepositoryImpl(
     private val handler: DatabaseHandler,
 ) : CategoryRepository {
 
+    override suspend fun get(id: Long): Category? {
+        return handler.awaitOneOrNull { categoriesQueries.getCategory(id, categoryMapper) }
+    }
+
     override suspend fun getAll(): List<Category> {
         return handler.awaitList { categoriesQueries.getCategories(categoryMapper) }
     }