Add more demo platforms (#8903)

esphome/components/demo/demo_button.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "esphome/components/button/button.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace demo {
+
+class DemoButton : public button::Button {
+ protected:
+  void press_action() override {}
+};
+
+}  // namespace demo
+}  // namespace esphome