Add do_sample argument for API demo

[sunyuhan19981208]

DESCRIPTION

Add do_sample argument for API demo, if do_sample = True random sampling strategy will be ultilized otherwise greedy.

TEST

case1: do_sample = True

curl http://localhost:19327/v1/completions: application/json"   -d '{   
    "prompt": "告诉我中国和美国分别各有哪些优点缺点",
    "max_tokens": 90,
    "temperature": 1.7,
    "num_beams": 1,"top_p": 1.0,
    "top_k": 40,"do_sample":true
  }'

{"id":"cmpl-tcDabq7k535kNiwpmMmyVu","object":"text_completion","created":1688105528,"model":"chinese-llama-alpaca","choices":[{"index":0,"text":"中国和美国的经济、科技、文化等各方面有相应的优点和问题"}]}

curl http://localhost:19327/v1/completions: application/json"   -d '{   
    "prompt": "告诉我中国和美国分别各有哪些优点缺点",
    "max_tokens": 90,
    "temperature": 1.7,
    "num_beams": 1,"top_p": 1.0,
    "top_k": 40,"do_sample":true
  }'

{"id":"cmpl-3dscn9a3qcLrh57dYGpLNa","object":"text_completion","created":1688105543,"model":"chinese-llama-alpaca","choices":[{"index":0,"text":"中国的优点为经济增长速度相对较快，国家重视科技创新和人才建设；缺点表现在资源有限、政府治理、环境与经济之间的冲突中。 美国的优点表现为在科技、经济、文化、全球化方面的强大和独特程度以及政府政策和社会的开放、竞争；它的制度、法律体系与民主选举制度等方面比较完善。缺点在于贫富悬殊严重，社会、性别、经济的不平等十分"}]}

case2: do_sample = False

curl http://localhost:19327/v1/completions   -H "Content-Type: application/json"   -d '{   
    "prompt": "告诉我中国和美国分别各有哪些优点缺点",
    "max_tokens": 90,
    "temperature": 1.7,
    "num_beams": 1,"top_p": 1.0,
    "top_k": 40,"do_sample": false
  }'

{"id":"cmpl-3Lxx2duPyZkQC9ogRmWeea","object":"text_completion","created":1688105560,"model":"chinese-llama-alpaca","choices":[{"index":0,"text":"中国的优点包括：历史悠久、文化底蕴深厚、人口众多、经济快速发展等。缺点包括：环境污染、教育不公、社会不公等。美国的优点包括：政治稳定、经济发达、科技领先等。缺点包括：种族歧视、贫富分化、枪支暴力等。"}]}

curl http://localhost:19327/v1/completions   -H "Content-Type: application/json"   -d '{   
    "prompt": "告诉我中国和美国分别各有哪些优点缺点",
    "max_tokens": 90,
    "temperature": 1.7,
    "num_beams": 1,"top_p": 1.0,
    "top_k": 40,"do_sample": false
  }'

{"id":"cmpl-3Csm9wFGwfj7zqC9pHa8JY","object":"text_completion","created":1688105573,"model":"chinese-llama-alpaca","choices":[{"index":0,"text":"中国的优点包括：历史悠久、文化底蕴深厚、人口众多、经济快速发展等。缺点包括：环境污染、教育不公、社会不公等。美国的优点包括：政治稳定、经济发达、科技领先等。缺点包括：种族歧视、贫富分化、枪支暴力等。"}]}