Make leveling_is_active a macro

Marlin/src/core/utility.cpp

Marlin/src/feature/bedlevel/bedlevel.cpp

Marlin/src/feature/bedlevel/bedlevel.h

Marlin/src/gcode/bedlevel/M420.cpp

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

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

Marlin/src/gcode/calibrate/G28.cpp

Marlin/src/gcode/calibrate/M48.cpp

Marlin/src/lcd/ultralcd.cpp

Marlin/src/lcd/ultralcd_impl_HD44780.h

Marlin/src/module/configuration_store.cpp

Marlin/src/module/motion.cpp

Marlin/src/module/planner.cpp

Marlin/src/module/probe.cpp

Marlin/src/module/tool_change.cpp