Combine G-code files into fewer units

Marlin/src/gcode/config/M200-M205.cpp

Marlin/src/gcode/config/M200.cpp

Marlin/src/gcode/config/M201.cpp

Marlin/src/gcode/config/M203.cpp

Marlin/src/gcode/config/M205.cpp

Marlin/src/gcode/control/M108.cpp

Marlin/src/gcode/control/M108_M112_M410.cpp

Marlin/src/gcode/control/M112.cpp

Marlin/src/gcode/control/M17.cpp

Marlin/src/gcode/control/M17_M18_M84.cpp

Marlin/src/gcode/feature/digipot/M907-M910.cpp

Marlin/src/gcode/feature/digipot/M908.cpp

Marlin/src/gcode/feature/digipot/M909.cpp

Marlin/src/gcode/feature/digipot/M910.cpp

Marlin/src/gcode/feature/fwretract/M207-M209.cpp

Marlin/src/gcode/feature/fwretract/M207.cpp

Marlin/src/gcode/feature/fwretract/M209.cpp

Marlin/src/gcode/feature/mixing/M163-M165.cpp

Marlin/src/gcode/feature/mixing/M164.cpp

Marlin/src/gcode/feature/mixing/M165.cpp