Heat bed & Z axis mod

I wanted a side chain bed wiring mod and something to stabilize the Z axis. I wasn't finding exactly what I wanted but saw 3 different things that had elements of what I wanted. This is a remix of 3 different things by silentcarrier (2765233 wide chain and bed mount), malakid (2832253 bearing mount), and svideo (1864625 side cover with z mount). I also stole the idea of a hex grid cooling vent from falconman (1975491).

I liked the idea of a wider chain so the connectors don't need to be remov