feat: implement native Unix Domain Socket support #1998

Job	Run time
Build old RabbitMQ	4m 4s
Build new RabbitMQ	4m 4s
Test 10k_queues_import + 1 node(s)	1m 13s
Test durable_queue + 1 node(s)	55s
Test durable_queue + 3 node(s)	1m 1s
Test topic_bindings_import + 1 node(s)	1m 6s
Test topic_bindings_import + 3 node(s)	1m 49s
Test transient_queue + 3 node(s)	1m 20s
Test 10k_queues_import + 3 node(s)	2m 14s
	17m 46s

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