Melzi board support frame for TronXY X1

I was inspired to make this after I saw the [Tronxy x3 control PCB cradle](https://www.thingiverse.com/thing:2775139) by [Richard Baldock](https://www.thingiverse.com/baldrick131/about).

This is a Melzi Board support frame that fits inside the TronXY X1 control box.