LibWeb: Correctly initialize Storage objects on the Document

Instead of storing all storage objects in static memory, we now
follow the the spec by lazily creating a unique Storage object
on each document object.

Each Storage object now holds a 'proxy' to the underlying backing
storage. For now, this proxy is simply a reference to the backing
object. In the future, it will need to be some type of interface
object that stores on a SQLite database or similar.

Session storage is now correctly stored / tracked as part of the
TraversableNavigable object.

Local storage is still stored in a static map, but eventually this
should be factored into something that is stored at the user agent
level.

Libraries/LibWeb/StorageAPI/StorageBottle.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2024-2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <AK/String.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/StorageAPI/StorageType.h>
+
+namespace Web::StorageAPI {
+
+// https://storage.spec.whatwg.org/#storage-bottle
+struct StorageBottle : public RefCounted<StorageBottle> {
+    static NonnullRefPtr<StorageBottle> create(Optional<u64> quota) { return adopt_ref(*new StorageBottle(quota)); }
+
+    // A storage bottle has a map, which is initially an empty map
+    OrderedHashMap<String, String> map;
+
+    // A storage bottle also has a proxy map reference set, which is initially an empty set
+    NonnullRefPtr<StorageBottle> proxy() { return *this; }
+
+    // A storage bottle also has a quota, which is null or a number representing a conservative estimate of
+    // the total amount of bytes it can hold. Null indicates the lack of a limit.
+    Optional<u64> quota;
+
+private:
+    explicit StorageBottle(Optional<u64> quota_)
+        : quota(quota_)
+    {
+    }
+};
+
+using BottleMap = OrderedHashMap<String, NonnullRefPtr<StorageBottle>>;
+
+// https://storage.spec.whatwg.org/#storage-bucket
+// A storage bucket is a place for storage endpoints to store data.
+struct StorageBucket {
+    explicit StorageBucket(StorageType);
+
+    // A storage bucket has a bottle map of storage identifiers to storage bottles.
+    BottleMap bottle_map;
+};
+
+RefPtr<StorageBottle> obtain_a_session_storage_bottle_map(HTML::EnvironmentSettingsObject&, StringView storage_identifier);
+RefPtr<StorageBottle> obtain_a_local_storage_bottle_map(HTML::EnvironmentSettingsObject&, StringView storage_identifier);
+RefPtr<StorageBottle> obtain_a_storage_bottle_map(StorageType, HTML::EnvironmentSettingsObject&, StringView storage_identifier);
+
+}