Switch Joycon Travel Tether

I needed an easy way to keep my JoyCons together when stowing them in the pocket of my steam deck case. Was stoked to see Print3DLLC had already designed something similar but bummed to discover it didn't fit the JoyCons as the original rails were too thick. So I modified his design to work properly. I also added notches so the JoyCon lock works and slimmed the entire thing down by about 3.5mm.