[SPARK-26451][SQL] Change lead/lag argument name from count to offset
[SPARK-26451][SQL] Change lead/lag argument name from count to offset

## What changes were proposed in this pull request?

Change aligns argument name with that in Scala version and documentation.

## How was this patch tested?

(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)
(If this patch involves UI changes, please attach a screenshot; otherwise, remove this)

Please review http://spark.apache.org/contributing.html before opening a pull request.

Closes #23357 from deepyaman/patch-1.

Authored-by: deepyaman <ae9c33d1937cc7cdfa5163e08a7b3e588940cc1a@utexas.edu>
Signed-off-by: Hyukjin Kwon <2680965ad5aae29275c8fb10150cb10f5554e78b@apache.org>

wzhfy/spark,rednaxelafx/apache-spark,xuanyuanking/spark,shuangshuangwang/spark,LantaoJin/spark,goldmedal/spark,kiszk/spark,zzcclp/spark,JoshRosen/spark,yanboliang/spark,vinodkc/spark,WeichenXu123/spark,spark-test/spark,hvanhovell/spark,jkbradley/spark,HyukjinKwon/spark,dbtsai/spark,yanboliang/spark,witgo/spark,rezasafi/spark,kiszk/spark,Aegeaner/spark,zzcclp/spark,aosagie/spark,kiszk/spark,facaiy/spark,xuanyuanking/spark,facaiy/spark,ptkool/spark,techaddict/spark,milliman/spark,guoxiaolongzte/spark,wangyum/spark,icexelloss/spark,shuangshuangwang/spark,hhbyyh/spark,BryanCutler/spark,mahak/spark,wangmiao1981/spark,caneGuy/spark,witgo/spark,wangmiao1981/spark,shaneknapp/spark,hhbyyh/spark,actuaryzhang/spark,zzcclp/spark,WindCanDie/spark,LantaoJin/spark,bdrillard/spark,taroplus/spark,WindCanDie/spark,skonto/spark,actuaryzhang/spark,wzhfy/spark,gengliangwang/spark,srowen/spark,zero323/spark,techaddict/spark,zero323/spark,dongjoon-hyun/spark,kevinyu98/spark,zuotingbing/spark,pgandhi999/spark,wzhfy/spark,goldmedal/spark,wangmiao1981/spark,srowen/spark,holdenk/spark,WeichenXu123/spark,jiangxb1987/spark,witgo/spark,srowen/spark,nchammas/spark,highfei2011/spark,nchammas/spark,skonto/spark,aosagie/spark,milliman/spark,hvanhovell/spark,jkbradley/spark,milliman/spark,Aegeaner/spark,yanboliang/spark,apache/spark,guoxiaolongzte/spark,nchammas/spark,dbtsai/spark,zero323/spark,darionyaphet/spark,skonto/spark,highfei2011/spark,rednaxelafx/apache-spark,cloud-fan/spark,aosagie/spark,wangyum/spark,hvanhovell/spark,vinodkc/spark,dongjoon-hyun/spark,ueshin/apache-spark,jiangxb1987/spark,BryanCutler/spark,nchammas/spark,pgandhi999/spark,zero323/spark,holdenk/spark,bdrillard/spark,chuckchen/spark,wzhfy/spark,rezasafi/spark,wzhfy/spark,vinodkc/spark,mahak/spark,zuotingbing/spark,spark-test/spark,gengliangwang/spark,dbtsai/spark,actuaryzhang/spark,darionyaphet/spark,Aegeaner/spark,zzcclp/spark,icexelloss/spark,zuotingbing/spark,ConeyLiu/spark,goldmedal/spark,kevinyu98/spark,WindCanDie/spark,ptkool/spark,skonto/spark,zzcclp/spark,shaneknapp/spark,apache/spark,holdenk/spark,apache/spark,jiangxb1987/spark,taroplus/spark,LantaoJin/spark,guoxiaolongzte/spark,icexelloss/spark,shuangshuangwang/spark,xuanyuanking/spark,aosagie/spark,maropu/spark,shaneknapp/spark,nchammas/spark,facaiy/spark,pgandhi999/spark,hhbyyh/spark,cloud-fan/spark,cloud-fan/spark,gengliangwang/spark,skonto/spark,wangyum/spark,rednaxelafx/apache-spark,taroplus/spark,caneGuy/spark,dbtsai/spark,shaneknapp/spark,vinodkc/spark,facaiy/spark,HyukjinKwon/spark,techaddict/spark,highfei2011/spark,apache/spark,kevinyu98/spark,kevinyu98/spark,chuckchen/spark,vinodkc/spark,goldmedal/spark,kiszk/spark,chuckchen/spark,ConeyLiu/spark,goldmedal/spark,shuangshuangwang/spark,zzcclp/spark,icexelloss/spark,dongjoon-hyun/spark,zzcclp/spark,spark-test/spark,apache/spark,ptkool/spark,mahak/spark,WeichenXu123/spark,guoxiaolongzte/spark,JoshRosen/spark,HyukjinKwon/spark,witgo/spark,rezasafi/spark,dongjoon-hyun/spark,hhbyyh/spark,zero323/spark,jiangxb1987/spark,yanboliang/spark,xuanyuanking/spark,kiszk/spark,ueshin/apache-spark,rezasafi/spark,ConeyLiu/spark,caneGuy/spark,hhbyyh/spark,hvanhovell/spark,bdrillard/spark,WindCanDie/spark,ueshin/apache-spark,WeichenXu123/spark,chuckchen/spark,hvanhovell/spark,darionyaphet/spark,aosagie/spark,ptkool/spark,shuangshuangwang/spark,gengliangwang/spark,HyukjinKwon/spark,apache/spark,pgandhi999/spark,kiszk/spark,mahak/spark,maropu/spark,xuanyuanking/spark,jiangxb1987/spark,LantaoJin/spark,holdenk/spark,mahak/spark,nchammas/spark,srowen/spark,hhbyyh/spark,facaiy/spark,facaiy/spark,highfei2011/spark,WeichenXu123/spark,techaddict/spark,chuckchen/spark,maropu/spark,wzhfy/spark,wangmiao1981/spark,jkbradley/spark,guoxiaolongzte/spark,WindCanDie/spark,ConeyLiu/spark,caneGuy/spark,shuangshuangwang/spark,darionyaphet/spark,maropu/spark,ptkool/spark,icexelloss/spark,kevinyu98/spark,icexelloss/spark,zuotingbing/spark,milliman/spark,spark-test/spark,zuotingbing/spark,wangmiao1981/spark,holdenk/spark,kevinyu98/spark,witgo/spark,holdenk/spark,facaiy/spark,spark-test/spark,dongjoon-hyun/spark,techaddict/spark,BryanCutler/spark,dongjoon-hyun/spark,yanboliang/spark,taroplus/spark,rezasafi/spark,nchammas/spark,maropu/spark,wangyum/spark,witgo/spark,ueshin/apache-spark,matthewfranglen/spark,actuaryzhang/spark,Aegeaner/spark,srowen/spark,caneGuy/spark,ueshin/apache-spark,goldmedal/spark,spark-test/spark,ueshin/apache-spark,hhbyyh/spark,pgandhi999/spark,LantaoJin/spark,skonto/spark,wangyum/spark,highfei2011/spark,darionyaphet/spark,guoxiaolongzte/spark,rezasafi/spark,pgandhi999/spark,cloud-fan/spark,rednaxelafx/apache-spark,rednaxelafx/apache-spark,wzhfy/spark,goldmedal/spark,dbtsai/spark,LantaoJin/spark,taroplus/spark,actuaryzhang/spark,Aegeaner/spark,milliman/spark,pgandhi999/spark,JoshRosen/spark,chuckchen/spark,ConeyLiu/spark,ptkool/spark,milliman/spark,xuanyuanking/spark,bdrillard/spark,guoxiaolongzte/spark,cloud-fan/spark,actuaryzhang/spark,BryanCutler/spark,darionyaphet/spa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