boards: arm: nordic: update DTS for nRF5340

Add a generic GPIO pin forwarder node to nRF5340 application core DTS
and to Thingy53 application core DTS. For Thingy53, add data of
FEM-related pins to the GPIO forwarder node. For nRF5340, leave the node
with status disabled by default.

Signed-off-by: Jedrzej Ciupis <jedrzej.ciupis@nordicsemi.no>