add group feature

src/group.cpp

@@ -0,0 +1,19 @@
+#include "group.hpp"
+#include <fmt/format.h>
+#include <util/command.hpp>
+
+namespace waybar {
+
+Group::Group(const std::string& name, const Bar& bar, const Json::Value& config)
+    : AModule(config, name, "", false, false),
+      box{bar.vertical ? Gtk::ORIENTATION_HORIZONTAL : Gtk::ORIENTATION_VERTICAL, 0}
+    {
+}
+
+auto Group::update() -> void {
+  // noop
+}
+
+Group::operator Gtk::Widget&() { return box; }
+
+}  // namespace waybar