Re-evaluate log switch logic for Log Miner implementation

During LogMinerStreamingChangeEventSource, if the amount of records that are processed in large, the switch can happen during the processing. The log switch check should probably happen more frequently. See https://github.com/debezium/debezium-incubator/pull/185#discussion_r478447579

During LogMinerQueryResultProcessor, there is a loop where it may make sense to check log switching. See https://github.com/debezium/debezium-incubator/pull/185#discussion_r478450054

Perhaps we should consider adding a configuration option that defines how often the log miner implementation checks for log switches and use this in these two locations.