Browser: Use `GUI::CommonActions::make_about_action()`

Browser had bespoke code for showing the exact same AboutDialog, in a
more convoluted way.

Userland/Applications/Browser/BrowserWindow.cpp

@@ -20,8 +20,6 @@
 #include <LibCore/DateTime.h>
 #include <LibCore/StandardPaths.h>
 #include <LibCore/Stream.h>
-#include <LibCore/Version.h>
-#include <LibGUI/AboutDialog.h>
 #include <LibGUI/Application.h>
 #include <LibGUI/Clipboard.h>
 #include <LibGUI/Icon.h>
@@ -131,11 +129,6 @@ BrowserWindow::BrowserWindow(CookieJar& cookie_jar, URL url)
         m_tab_widget->activate_last_tab();
     });
 
-    m_window_actions.on_about = [this] {
-        auto app_icon = GUI::Icon::default_icon("app-browser"sv);
-        GUI::AboutDialog::show("Browser"sv, Core::Version::read_long_version_string(), app_icon.bitmap_for_size(32), this);
-    };
-
     m_window_actions.on_show_bookmarks_bar = [](auto& action) {
         Browser::BookmarksBarWidget::the().set_visible(action.is_checked());
         Config::write_bool("Browser"sv, "Preferences"sv, "ShowBookmarksBar"sv, action.is_checked());

Userland/Applications/Browser/WindowActions.cpp

@@ -75,13 +75,7 @@ WindowActions::WindowActions(GUI::Window& window)
         &window));
     m_tab_actions.last().set_status_tip("Switch to last tab");
 
-    m_about_action = GUI::Action::create(
-        "&About Browser", GUI::Icon::default_icon("app-browser"sv).bitmap_for_size(16), [this](const GUI::Action&) {
-            if (on_about)
-                on_about();
-        },
-        &window);
-    m_about_action->set_status_tip("Show application about box");
+    m_about_action = GUI::CommonActions::make_about_action("Browser", GUI::Icon::default_icon("app-browser"sv), &window);
 
     m_show_bookmarks_bar_action = GUI::Action::create_checkable(
         "&Bookmarks Bar", { Mod_Ctrl, Key_B },

Userland/Applications/Browser/WindowActions.h

@@ -22,7 +22,6 @@ public:
     Function<void()> on_next_tab;
     Function<void()> on_previous_tab;
     Vector<Function<void()>> on_tabs;
-    Function<void()> on_about;
     Function<void(GUI::Action&)> on_show_bookmarks_bar;
     Function<void(GUI::Action&)> on_vertical_tabs;