Add "Marlin Dev Mode" option

Marlin/Configuration_adv.h

Marlin/src/config/default/Configuration_adv.h

...src/config/examples/AlephObjects/TAZ4/Configuration_adv.h

Marlin/src/config/examples/Anet/A6/Configuration_adv.h

Marlin/src/config/examples/Anet/A8/Configuration_adv.h

Marlin/src/config/examples/Azteeg/X5GT/Configuration_adv.h

...c/config/examples/BIBO/TouchX/cyclops/Configuration_adv.h

...c/config/examples/BIBO/TouchX/default/Configuration_adv.h

Marlin/src/config/examples/BQ/Hephestos/Configuration_adv.h

...in/src/config/examples/BQ/Hephestos_2/Configuration_adv.h

Marlin/src/config/examples/BQ/WITBOX/Configuration_adv.h

Marlin/src/config/examples/Cartesio/Configuration_adv.h

...in/src/config/examples/Creality/CR-10/Configuration_adv.h

...n/src/config/examples/Creality/CR-10S/Configuration_adv.h

...rc/config/examples/Creality/CR-10mini/Configuration_adv.h

Marlin/src/config/examples/Creality/CR-8/Configuration_adv.h

.../src/config/examples/Creality/Ender-2/Configuration_adv.h

.../src/config/examples/Creality/Ender-3/Configuration_adv.h

.../src/config/examples/Creality/Ender-4/Configuration_adv.h

Marlin/src/config/examples/Felix/Configuration_adv.h