Add the ability to take screenshots

Add the ability to take screenshots

The option to simply take screenshots directly on the AIO-6 would be invaluable. Screenshots should be stored on the micro SD card as .jpg or .png files. Chigee themselves actually requests screenshots from owners for tech support problems (e.g. AIO-6 Max and LTE straight line GPX track problem), but we instead have to submit phone camera pics. Please, it's a ridiculous oversight not to offer this.