Differentiate translated On/Off from Serial ON/OFF

Marlin/src/core/language.h

Marlin/src/core/serial.cpp

Marlin/src/core/serial.h

Marlin/src/gcode/bedlevel/M420.cpp

Marlin/src/gcode/bedlevel/mbl/G29.cpp

Marlin/src/gcode/control/M211.cpp

Marlin/src/gcode/control/M605.cpp

Marlin/src/lcd/language/language_an.h

Marlin/src/lcd/language/language_bg.h

Marlin/src/lcd/language/language_ca.h

Marlin/src/lcd/language/language_cz.h

Marlin/src/lcd/language/language_da.h

Marlin/src/lcd/language/language_de.h

Marlin/src/lcd/language/language_el-gr.h

Marlin/src/lcd/language/language_el.h

Marlin/src/lcd/language/language_en.h

Marlin/src/lcd/language/language_es.h

Marlin/src/lcd/language/language_eu.h

Marlin/src/lcd/language/language_fi.h

Marlin/src/lcd/language/language_fr.h