Added 4 grayscale support to epd

Client/main/main.cpp

@@ -77,9 +77,9 @@ extern "C" void app_main()
 
   ESP_LOGI(TAG, "Initializing EPD");
   epd_init();
-  epd_init_display();
+  epd_init_display(true);
   // epd_clear(epd_color::WHITE);
-  epd_draw_bitmap(epd_color::WHITE, test_image);
+  epd_draw_bitmap_grayscale(epd_color::WHITE, gImage_4G1);
   epd_refresh();
   epd_shutdown_display();