added velocity calculation to StepDirListener for use in FF #786

Job	Run time
Test compiling (arduino:avr:uno)	2m 37s
Test compiling (arduino:sam:arduino_due_x)	55s
Test compiling (arduino:avr:mega)	35s
Test compiling (arduino:avr:leonardo)	24s
Test compiling (arduino:samd:nano_33_iot)	3m 9s
Test compiling (adafruit:samd:adafruit_metro_m4)	2m 4s
Test compiling (esp32:esp32:esp32doit-devkit-v1)	4m 22s
Test compiling (esp32:esp32:esp32s2)	2m 50s
Test compiling (esp32:esp32:esp32s3)	3m 14s
Test compiling (STMicroelectronics:stm32:GenF1:pnum=BLUEPILL_F103C8)	3m 23s
Test compiling (STMicroelectronics:stm32:Nucleo_64:pnum=NUCLEO_F411RE)	6m 58s
Test compiling (STMicroelectronics:stm32:GenF4:pnum=GENERIC_F405RGTX)	3m 14s
Test compiling (STMicroelectronics:stm32:GenL4:pnum=GENERIC_L475RGTX)	7m 59s
Test compiling (STMicroelectronics:stm32:Disco:pnum=B_G431B_ESC1)	1m 38s
Test compiling (arduino:mbed_rp2040:pico)	1m 14s
	44m 36s

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