ports/nrf: enable json module on nrf boards generally
ports/nrf: enable json module on nrf boards generally

adafruit/circuitpython,adafruit/circuitpython,adafruit/circuitpython,adafruit/micropython,adafruit/circuitpython,adafruit/circuitpython,adafruit/micropython,adafruit/micropython,adafruit/micropython,adafruit/micropython,adafruit/circuitpython