Add new benchmark testing initialize performance (#478) #1762

Job	Run time
benchmark-run-once	1m 39s
benchmark-graph	41s
benchmark-default (ruby)	13m 57s
benchmark-ractor (head)	6m 53s
test (ruby)	45s
benchmark-ractor-only (head)	37s
test (truffleruby)	1m 48s
benchmark-default (head)	12m 30s
test (head)	42s
benchmark-default (truffleruby, --excludes=knucleotide,lobsters,ruby-lsp,shipit)	13m 0s
all-tests	2s
	52m 34s

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