Add new benchmark for getivar with T_CLASS and T_MODULE #1519

Job	Run time
benchmark-default (ruby)	10m 50s
benchmark-default (truffleruby)	16m 11s
benchmark-default (head)	10m 49s
test (ruby)	1m 4s
test (truffleruby)	59s
test (head)	1m 4s
benchmark-graph	1m 1s
benchmark-run-once	1m 37s
benchmark-ractor (head)	12m 38s
benchmark-ractor-only (ruby)	54s
benchmark-ractor-only (head)	49s
benchmark-ractor (ruby)	13m 31s
all-tests	3s
	1h 11m 30s

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