Utilize more heatset inserts on electronics box corners

[lostapathy]

Right now it's quite a lot of work to take any of the side panels off the electronics enclosure since they are all secured with nuts and bolts and access to the nuts is challenging.

Electronics box corners that used heatset inserts for all screws would make it possible to remove any side of the panel individually.

This would make it a lot easier to remove the front panel to gain access to the SD card, for one example.

[lostapathy]

Published an STL for this https://www.thingiverse.com/thing:3748830