Ladybird: Implement a JavaScript console for the AppKit chrome

This adds menu items to open an interactive JavaScript console for a web
page. This more or less mimics the Qt implementation of the console.
Hooks are included to tie the lifetime of the console window with the
tab it belongs to; if the tab is closed, the console window is closed.

Ladybird/AppKit/UI/LadybirdWebView.mm

@@ -112,6 +112,11 @@ struct HideCursor {
     m_web_view_bridge->load_html(html, url);
 }
 
+- (WebView::ViewImplementation&)view
+{
+    return *m_web_view_bridge;
+}
+
 - (String const&)handle
 {
     return m_web_view_bridge->handle();