Support multi-process debugging: sync breakpoints and coordinate instances #1804

Job	Run time
ruby-versions / Generate Ruby versions	3s
test (2.7)	1m 57s
test (3.3)	1m 54s
test (head)	1m 47s
test (3.0)	1m 42s
test (3.2)	1m 50s
test (4.0)	1m 50s
test (3.4)	1m 51s
test (debug)	6m 13s
test (3.1)	1m 48s
	20m 55s

Provide feedback