Adapt the new UI for heltec e290.

variants/heltec_vision_master_e290/target.h

@@ -9,6 +9,7 @@
 #include <helpers/SensorManager.h>
 #ifdef DISPLAY_CLASS
 #include <helpers/ui/E290Display.h>
+#include <helpers/ui/MomentaryButton.h>
 #endif
 
 extern HeltecE290Board board;
@@ -18,6 +19,7 @@ extern SensorManager sensors;
 
 #ifdef DISPLAY_CLASS
 extern DISPLAY_CLASS display;
+extern MomentaryButton user_btn;
 #endif
 
 bool radio_init();