Everywhere: Implement persistence of localStorage using sqlite

This change follows the pattern of our cookies persistence
implementation: the "browser" process is responsible for interacting
with the sqlite database, and WebContent communicates all storage
operations via IPC.

The new database table uses (storage_endpoint, storage_key, bottle_key)
as the primary key. This design follows concepts from the
https://storage.spec.whatwg.org/ and is intended to support reuse of the
persistence layer for other APIs (e.g., CacheStorage, IndexedDB). For
now, `storage_endpoint` is always "localStorage", `storage_key` is the
website's origin, and `bottle_key` is the name of the localStorage key.

Libraries/LibWebView/Application.h

@@ -22,6 +22,7 @@
 #include <LibWebView/Process.h>
 #include <LibWebView/ProcessManager.h>
 #include <LibWebView/Settings.h>
+#include <LibWebView/StorageJar.h>
 
 namespace WebView {
 
@@ -46,6 +47,7 @@ public:
     static ImageDecoderClient::Client& image_decoder_client() { return *the().m_image_decoder_client; }
 
     static CookieJar& cookie_jar() { return *the().m_cookie_jar; }
+    static StorageJar& storage_jar() { return *the().m_storage_jar; }
 
     static ProcessManager& process_manager() { return *the().m_process_manager; }
 
@@ -138,6 +140,7 @@ private:
 
     RefPtr<Database> m_database;
     OwnPtr<CookieJar> m_cookie_jar;
+    OwnPtr<StorageJar> m_storage_jar;
 
     OwnPtr<Core::TimeZoneWatcher> m_time_zone_watcher;