`atom.INTERNAL_onInit` hook to support sync effects #4224

Job	Run time
test	54s
test_matrix (16.14.0)	54s
test_matrix (17.0.0)	59s
test_matrix (18.0.0)	55s
test_matrix (18.1.0)	54s
test_matrix (18.2.0)	51s
test_matrix (18.3.1)	51s
test_matrix (19.0.0)	57s
test_matrix (19.1.0-canary-4dff0e62-20241213)	57s
test_matrix (0.0.0-experimental-4dff0e62-20241213)	59s
	9m 11s

Provide feedback