Support IELR(1) Parser Generation #1396

Job	Run time
steep-check (head)	17s
test-ruby (head, master)	6m 5s
check-misc (head)	7s
test-memory (head)	51m 31s
test-ruby (3.0, master)	5m 46s
test-windows (head)	22m 7s
ruby-versions / Generate Ruby versions	4s
test-cpp (head, g++)	53m 29s
test (2.5)	1h 14m 3s
test-cpp (head, clang++)	52m 38s
test (2.6)	1h 27m 31s
test (2.7)	1h 27m 28s
test (3.0)	49m 47s
test (3.1)	51m 15s
test (3.2)	53m 24s
test (3.3)	55m 20s
test (head)	52m 59s
	11h 43m 51s

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