Allow SERIAL_ECHOPAIR to take up to 12 pairs (#13311)

Marlin/src/Marlin.cpp

Marlin/src/core/minmax.h

Marlin/src/core/serial.cpp

Marlin/src/core/serial.h

Marlin/src/feature/I2CPositionEncoder.cpp

Marlin/src/feature/I2CPositionEncoder.h

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

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

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

Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp

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

Marlin/src/feature/dac/stepper_dac.cpp

Marlin/src/feature/fwretract.cpp

Marlin/src/feature/mixing.cpp

Marlin/src/feature/mixing.h

Marlin/src/feature/pause.cpp

Marlin/src/feature/power_loss_recovery.cpp

Marlin/src/feature/prusa_MMU2/mmu2.cpp

Marlin/src/feature/twibus.cpp

Marlin/src/gcode/bedlevel/G26.cpp