Add telemetry for producer, producer_consumer & consumer

[vasuadari]

Producer

• When producer starts(flume.producer.init = system_time)
• No. of events fetched(flume.producer.events.fetch = 10)
• Time taken to fetch events(flume.producer.events.fetch.stop)
• metadata for all events
  • :pipeline_name - name of the pipeline for which producer is running
  • :queue_name - name of the queue in the redis
  • :rate_limit_count - no. of events that can be processed by the consumer
  • :rate_limit_scale - duration for which no. of events as per rate_limit_count can be processed
  • :rate_limit_key - unique key for which rate limit is applied
  • :max_demand - Maximum number of jobs to pull from the queue

ProducerConsumer

• When producer consumer starts(flume.producer_consumer.init = system_time)
• No. of events fetched(flume.producer_consumer.events.received = 10)

Consumer

• When consumer starts(flume.consumer.init = system_time)

cc @nitinstp23