Add a16w8 per-op test for bmm (#19599) #5655

Job	Run time
test-coreml / test-backend-macos (coreml_static_int8, operators) / macos-job	2h 0m 57s
test-coreml / test-backend-macos (coreml_static_int8, models) / macos-job	25m 48s
test-coreml / test-backend-macos (coreml, models) / macos-job	12m 51s
test-coreml / test-backend-macos (coreml, operators) / macos-job	10m 30s
test-coreml / package-golden-artifacts	0s
test-coreml / test-backend-linux	-6s
	2h 50m 0s

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