Add yaml pipeline examples

[Amar3tto]

Beam YAML pipelines added:

1. Csv to Json
2. Kafka to Json
3. BigQuery to Kafka
4. Kafka to BigQuery

[Amar3tto]

One note:
When running the Kafka to BigQuery pipeline, the following logging error occurs:
Previous channel ManagedChannelImpl{logId=17, target=localhost:12371} was not shutdown properly!!!
boot.go: error logging message over FnAPI. endpoint localhost:12370 error: EOF message follows
It seems like this error is something similar to the known issue: apache/beam#29683

[damccorm]

Could we add an example MapToFields and Filter to these? Doesn't need to be complicated, something similar to the csv_to_json filter is fine

[Amar3tto]

Done

[damccorm]

Thanks!