Move UI folder

UI/UI_button.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "UI_item.hpp"
+
+#define UI_BUTTON_TYPE std::string("UI_button")
+
+class UI_button : public UI_item
+{
+    Q_OBJECT
+  public:
+    UI_button(std::string text, Color fg_color, Color bg_color, QObject *parent = nullptr);
+    UI_button(const json &j, QObject *parent = nullptr);
+
+    void from_json(const json &j) override;
+    json to_json(size_t id) const override;
+
+    void click() override;
+
+  signals:
+    void on_click();
+};