Add LLaMA perf benchmark workflow for Apple iOS #6

Job	Run time
set-parameters	14s
export-models (stories110M, xnnpack) / macos-job	12m 29s
upload-models	18s
build-llm-demo (bpe, stories110M, xnnpack) / macos-job	13m 21s
upload-ios-apps	0s
	26m 22s

Provide feedback