Add prometheus metrics pytvzhen_api_request_counter.

[HanFa]

# HELP pytvzhen_api_request_counter_total Request count by request paths
# TYPE pytvzhen_api_request_counter_total counter
pytvzhen_api_request_counter_total{base_url="/yt_download",method="POST",stage="devo",status="200"} 1.0
pytvzhen_api_request_counter_total{base_url="/yt",method="GET",stage="devo",status="200"} 1.0
pytvzhen_api_request_counter_total{base_url="/yt",method="GET",stage="devo",status="404"} 1.0
# HELP pytvzhen_api_request_counter_created Request count by request paths
# TYPE pytvzhen_api_request_counter_created gauge
pytvzhen_api_request_counter_created{base_url="/yt_download",method="POST",stage="devo",status="200"} 1.7176584670508301e+09
pytvzhen_api_request_counter_created{base_url="/yt",method="GET",stage="devo",status="200"} 1.717658468841056e+09
pytvzhen_api_request_counter_created{base_url="/yt",method="GET",stage="devo",status="404"} 1.7176584888814e+09