Support multi-process debugging: sync breakpoints and coordinate instances #1803

Job	Run time
ruby-versions / Generate Ruby versions	5s
test (3.4)	1m 48s
test (3.1)	1m 49s
test (3.3)	1m 50s
test (2.7)	1m 57s
test (3.0)	1m 39s
test (4.0)	1m 53s
test (3.2)	1m 46s
test (head)	1m 51s
test (debug)	6m 14s
	20m 52s

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