Add a feedRate_t data type (#15349)

Marlin/src/core/macros.h

Marlin/src/feature/I2CPositionEncoder.cpp

Marlin/src/feature/bedlevel/abl/abl.cpp

Marlin/src/feature/bedlevel/abl/abl.h

Marlin/src/feature/bedlevel/mbl/mesh_bed_leveling.cpp

Marlin/src/feature/bedlevel/mbl/mesh_bed_leveling.h

Marlin/src/feature/bedlevel/ubl/ubl.h

Marlin/src/feature/bedlevel/ubl/ubl_motion.cpp

Marlin/src/feature/fwretract.cpp

Marlin/src/feature/fwretract.h

Marlin/src/feature/pause.cpp

Marlin/src/feature/pause.h

Marlin/src/feature/prusa_MMU2/mmu2.cpp

Marlin/src/gcode/bedlevel/G26.cpp

Marlin/src/gcode/bedlevel/G42.cpp

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

Marlin/src/gcode/calibrate/G425.cpp

Marlin/src/gcode/feature/L6470/M916-918.cpp

Marlin/src/gcode/feature/camera/M240.cpp

Marlin/src/gcode/feature/pause/M701_M702.cpp