This is a leftover from the Gateway era that has long lost its utility
and that unnecessarily complicated the code base.
Please just load an external FIRM from SD card if you need something
similar.
Also refactor the multi-EmuNAND code and CTRNAND mounting code.
For stuff like testing PASLR, *hax2x, khc3ds, etc.
Also fix a corner-case bug when changing the 3dsx app from itself to
itself, if its TID corresponds to the default.
- Stop spamming mcu reads... use the GPIO pin to know if there's a MCU interrupt, instead
- Wait for the MCU interrupts to be raised when powering up LCD+backlights
- Also turn off LCD+backlight when needed