Add E3D Rumba Pins to support E3D BigBox Printers

[RainMotorsports]

Description

The E3D BigBox printers did not use the thermistor ports for the hotends which requires editing the pins file. I intend to contribute configuration(s) for this printer and would like to have proper support where the user only needs the configuration.h/configuration_adv.h.

I used 2 things to guide this. Raise3D has a similar pins include/board definition for Rumba. I also used the original pins changes by E3D for 1.x.x as a reference. https://github.com/BigBox3D/Marlin/blob/RC/Marlin/pins_RUMBA.h.

Requirements

Rumba Board, E3D PT100 amplifier boards connected to pins 10 and 9 (EXP3).

Benefits

Adds standard support for stock E3D BigBox models.

Configurations

I have not completed a 2.1.3/recent bugfix config for this printer (last was 2.1.2.4) so I am not attaching a config at this time unless it is deemed necessary. I will have that done soon.

[ellensp]

This is failing.

"make validate-boards -j : Validate boards.h and pins.h for standards compliance"

The changes you made in pins.h and boards.h are in different locations.
Need to keep the same order of motherboards

[RainMotorsports]

This is failing.

"make validate-boards -j : Validate boards.h and pins.h for standards compliance"

The changes you made in pins.h and boards.h are in different locations. Need to keep the same order of motherboards

Thank you. I was not sure what the problem was. I believe I have corrected it but am new to GitHub so if there is anything additional I need to do please let me know.

Im running this on the printer. Was delayed a day or so in getting the config done because I had to fix a hardware issue. Should have it done within the day if thats needed but contributing it to the config repo of course relies on this end of it.

[ellensp]

All checks have passed, looks good to go.

[RainMotorsports]

All checks have passed, looks good to go.

Seems to keep failing these days on something that i would think is not related but maybe I did something wrong? I wasn't sure what to do while i wait, so i tried syncing to keep it up to date.