Fix large cache size (#437)

* Add custom cache manager

* Fix

* Add cleanup

* Remove prints for debugging

* Remove unnecessary code

* Change nr of max cache objects

lib/cache_manager.dart

@@ -0,0 +1,44 @@
+import 'dart:io';
+
+import 'package:flutter_cache_manager/flutter_cache_manager.dart';
+import 'package:path_provider/path_provider.dart';
+
+class CustomCacheManager {
+  static const key = 'libCachedImageData';
+  static final _repo = CacheObjectProvider(databaseName: key);
+  static final instance = CacheManager(
+    Config(
+      key,
+      stalePeriod: const Duration(days: 30),
+      maxNrOfCacheObjects: 10000,
+      repo: _repo,
+    ),
+  );
+
+  static Future<void> removeOrphanedCacheFiles() async {
+    final tempDir = await getTemporaryDirectory();
+    final cacheDir = Directory('${tempDir.path}/$key');
+
+    if (!await cacheDir.exists()) {
+      return;
+    }
+
+    final allFiles = cacheDir.listSync(recursive: true).toList();
+
+    await _repo.open();
+    final cachedObjects = await _repo.getAllObjects();
+    final dbFiles = cachedObjects.map((e) => e.relativePath).toSet();
+
+    final orphanedFiles = allFiles.where((file) {
+      final relativePath = file.path.split('$key/').last;
+      return !dbFiles.contains(relativePath);
+    }).toList();
+
+    final deletions = orphanedFiles.map((file) => file.delete()).toList();
+
+    try {
+      await Future.wait(deletions);
+      // ignore: empty_catches
+    } catch (e) {}
+  }
+}