Creality Ender 3 - PSU cover upgrade with USB

Upgrades the ender 3 psu cover by adding a 2 X60 plugs and 2 (QC3) USB ports.

Uses the stock switch/power connector assembly.

The USB ports are provided by [these](https://www.aliexpress.com/item/QC3-0-QC2-0-USB-DC-DC-Buck-Converter-Charging-Step-Down-Module-6-32V-9V/32671645129.html) USB buck converters which can be powered directly from the 24V rails.

The X60 connectors fit tightly and should stay in place without glue, for the USB ports I added some hot glue at the back to keep them