Ethernet, initCallback, ctor and eth_if #1121

Job	Run time
compile-examples (arduino:mbed:nano33ble)	8m 7s
compile-examples (arduino:mbed:envie_m7)	17m 3s
compile-examples (arduino:mbed:nanorp2040connect)	13m 55s
compile-examples (arduino:mbed:nicla_sense)	7m 40s
compile-examples (arduino:mbed:nicla_vision)	13m 48s
compile-examples (arduino:mbed:opta)	17m 18s
compile-examples (arduino:mbed:giga)	25m 46s
compile-examples (arduino:mbed:nicla_voice)	5m 53s
compile-examples (arduino:mbed:edge_control)	5m 58s
compile-examples (arduino:mbed:envie_m7:target_core=cm4, - libraries/KernelDebug - libraries/Port...	4m 42s
	2h 0m 10s

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