FW3.14.1 for MK3S with MMU12x

This is a community firmware release for the MMU12x based on Prusa Firmware version 3.14.1

More about the MMU12x project please checkout https://github.com/cjbaar/prusa-mmu-12x by @cjbaar

Summary

• New variant MK3S_MMU12x.h
  • Only difference to the MK3S.h variant is that #define MMU_FILAMENT_COUNT value changed from 5 to `12
• Updated firmware to support more than 5 tools
  • Unknown Filament slot is now shown as -1 instead of ?

❗ As this is a community firmware, please don't try to get support from Prusa ❗

I don't have a MMU12x but I like the project and try to help the community with this firmware release.

In case you have an issue, please checkout cjbaar repository and report it there.
If the question is 8-bit firmware related, feel free to tag me in that repository issue tracker.

It makes most sense to keep the issues there.