Cadence Indexer (uber#1341)

* Cadence Index Processor

* Add DLQ for visibility

* Improve logging

* Add metrics

* make index configurable

* Fix unit tests

* Improve err handling

* Make defaultEnableVisibilityToKafka configurable

* Make enableVisibilityToKafka configurable

* Add unit tests

* Refactor bulkAfterAction

* fix config init

* Add more tests

* Update thrift to be more generic

* Remove deduplicate in add

* Use metricsProducer for visibility producer

* Clean getVisibilityProducer with metricsClient

* Address comments and make code cleaner