Get all mailbox cache by AccountId

(cherry picked from commit 8a7ccbf5d757ac9f1ffbd1fc5a1c863f30ab7b4c)

core/lib/core.dart

@@ -13,6 +13,7 @@ export 'presentation/extensions/compare_list_extensions.dart';
 export 'presentation/extensions/string_extension.dart';
 export 'presentation/extensions/tap_down_details_extension.dart';
 export 'domain/extensions/media_type_extension.dart';
+export 'presentation/extensions/map_extensions.dart';
 
 // Exceptions
 export 'domain/exceptions/download_file_exception.dart';

core/lib/presentation/extensions/map_extensions.dart

@@ -0,0 +1,13 @@
+
+extension MapExtensions<K, V> on Map<K, V> {
+
+  Map<K, V> where(bool Function(K, V) condition) {
+    Map<K, V> result = {};
+    for (var element in entries) {
+      if (condition(element.key, element.value)) {
+        result[element.key] = element.value;
+      }
+    }
+    return result;
+  }
+}