Add kvcache convert to fp16 for StaticLLMPipeline (#898) #1

Job	Run time
cpp-beam_search_causal_lm-Phi-2	1s
cpp-beam_search_causal_lm-notus-7b-v1	1s
cpp-beam_search_causal_lm-Qwen1_5-7B-Chat	1s
cpp-beam_search_causal_lm-Qwen-7B-Chat	1s
cpp-beam_search_causal_lm-ubuntu (./build/samples/cpp/beam_search_causal_lm/beam_search_causal_lm)	14m 47s
cpp-chat_sample-ubuntu	11m 31s
cpp-beam_search_causal_lm-ubuntu (python ./samples/python/beam_search_causal_lm/beam_search_causa...	13m 2s
cpp-continuous-batching-macos	17m 51s
cpp-continuous-batching-ubuntu	1s
cpp-continuous-batching-windows	0s
cpp-greedy_causal_lm-redpajama-3b-chat	1s
cpp-greedy_causal_lm-windows	0s
cpp-multinomial-greedy_causal_lm-ubuntu	1s
cpp-Phi-1_5	1s
cpp-prompt_lookup_decoding_lm-ubuntu	1s
cpp-speculative_decoding_lm-ubuntu	1s
ci/gha_overall_status_causal_lm	1s
	57m 22s

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