Fix handling of multiple interfaces in UnixUdpNetwork #116

Job	Run time
extras	35s
pio-merge (vest)	1m 16s
check-format	6s
pio-build (vest_dev)	1m 9s
pio-merge (vest_s3)	2m 29s
pio-build (vest_instrumentation)	3m 16s
pio-merge (shoe)	1m 14s
pio-native-test	17s
pio-build (clouds_s3_debug)	2m 34s
pio-merge (hat)	1m 11s
pio-build (gauntlet)	1m 27s
pio-build (vest_idf5)	1m 34s
pio-build (vest_idf5_espidf)	5m 22s
pages	0s
	22m 30s

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