LibGUI: Add PathBreadcrumbbar

This Widget wraps both a Breadcrumbbar and a TextBox for editing the
path manually, based heavily on the existing code in FileManager.

Breadcrumbbar itself requires outside code to micro-manage what it does.
This class provides a simpler interface for it: Users don't have to
worry about segments, they just give/receive a string for the current
path.

Userland/Libraries/LibGUI/PathBreadcrumbbar.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2023, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtr.h>
+#include <LibGUI/Forward.h>
+#include <LibGUI/Widget.h>
+
+namespace GUI {
+
+class PathBreadcrumbbar : public Widget {
+    C_OBJECT_ABSTRACT(PathBreadcrumbbar)
+public:
+    static ErrorOr<NonnullRefPtr<PathBreadcrumbbar>> try_create();
+    virtual ~PathBreadcrumbbar() override;
+
+    void set_current_path(DeprecatedString const&);
+
+    void show_location_text_box();
+    void hide_location_text_box();
+
+    bool has_parent_segment() const;
+    bool has_child_segment() const;
+
+    void select_parent_segment();
+    void select_child_segment();
+
+    Function<void(StringView path)> on_path_change;
+    Function<void(StringView path, GUI::DropEvent const&)> on_paths_drop;
+    Function<void()> on_hide_location_box;
+
+private:
+    PathBreadcrumbbar(NonnullRefPtr<GUI::TextBox>, NonnullRefPtr<GUI::Breadcrumbbar>);
+
+    NonnullRefPtr<GUI::TextBox> m_location_text_box;
+    NonnullRefPtr<GUI::Breadcrumbbar> m_breadcrumbbar;
+
+    DeprecatedString m_current_path;
+};
+
+}