Ladybird: Add a location bar and allow navigating to new pages :^)

Ladybird/BrowserWindow.h

@@ -0,0 +1,23 @@
+#include <QLineEdit>
+#include <QMainWindow>
+#include <QToolBar>
+
+#pragma once
+
+class WebView;
+
+class BrowserWindow : public QMainWindow {
+    Q_OBJECT
+public:
+    BrowserWindow();
+
+    WebView& view() { return *m_view; }
+
+public slots:
+    void location_edit_return_pressed();
+
+private:
+    QToolBar* m_toolbar { nullptr };
+    QLineEdit* m_location_edit { nullptr };
+    WebView* m_view { nullptr };
+};