Group related client functions together
Group related client functions together

Also add some missing godoc. No functional changes.

kraveio/sarama,remerge/sarama,aybabtme/sarama,kmiku7/sarama,mailgun/sarama,aybabtme/sarama,jimmykuo/sarama,LastManStanding/sarama,remerge/sarama,jepst/sarama,Shopify/sarama,rafrombrc/sarama,winlinvip/sarama,yangfan876/sarama,betable/sarama,LastManStanding/sarama,VividCortex/sarama,crast/sarama,yangfan876/sarama,vrischmann/sarama,kraveio/sarama,mailgun/sarama,scalingdata/sarama,cep21/sarama,pronix/sarama,winlinvip/sarama,vrischmann/sarama,uovobw/sarama,pronix/sarama,crast/sarama,cep21/sarama,rafrombrc/sarama,uovobw/sarama,scalingdata/sarama,DataDog/sarama,raisemarketplace/sarama,jepst/sarama,betable/sarama,HelixEducation/sarama,raisemarketplace/sarama,Neuw84/sarama,DataDog/sarama,HelixEducation/sarama,kmiku7/sarama,jimmykuo/sarama,Neuw84/sarama,VividCortex/sarama,Shopify/sarama