Cleanup char tests (#7613)
Cleanup char tests (#7613)

* Cleanup char tests

- Take advantage of xunit
- Split up some tests to ensure tests only test a single thing

Contributes to #6286
seanshpark/corefx,stone-li/corefx,cydhaselton/corefx,rahku/corefx,manu-silicon/corefx,khdang/corefx,alexperovich/corefx,jlin177/corefx,cartermp/corefx,twsouthwick/corefx,jhendrixMSFT/corefx,alexperovich/corefx,twsouthwick/corefx,JosephTremoulet/corefx,axelheer/corefx,ptoonen/corefx,dsplaisted/corefx,marksmeltzer/corefx,wtgodbe/corefx,iamjasonp/corefx,SGuyGe/corefx,Chrisboh/corefx,shimingsg/corefx,dsplaisted/corefx,shmao/corefx,twsouthwick/corefx,wtgodbe/corefx,cydhaselton/corefx,JosephTremoulet/corefx,MaggieTsang/corefx,fgreinacher/corefx,mazong1123/corefx,seanshpark/corefx,elijah6/corefx,mmitche/corefx,ViktorHofer/corefx,zhenlan/corefx,stephenmichaelf/corefx,billwert/corefx,alexperovich/corefx,elijah6/corefx,YoupHulsebos/corefx,shahid-pk/corefx,ericstj/corefx,Petermarcu/corefx,axelheer/corefx,Ermiar/corefx,krk/corefx,Jiayili1/corefx,manu-silicon/corefx,JosephTremoulet/corefx,ericstj/corefx,yizhang82/corefx,zhenlan/corefx,billwert/corefx,tijoytom/corefx,wtgodbe/corefx,jhendrixMSFT/corefx,elijah6/corefx,dotnet-bot/corefx,lggomez/corefx,shmao/corefx,ellismg/corefx,ravimeda/corefx,Ermiar/corefx,richlander/corefx,JosephTremoulet/corefx,weltkante/corefx,Ermiar/corefx,ptoonen/corefx,nchikanov/corefx,elijah6/corefx,BrennanConroy/corefx,ViktorHofer/corefx,zhenlan/corefx,nchikanov/corefx,stone-li/corefx,krytarowski/corefx,khdang/corefx,dotnet-bot/corefx,alphonsekurian/corefx,ptoonen/corefx,krytarowski/corefx,dotnet-bot/corefx,nbarbettini/corefx,mazong1123/corefx,shimingsg/corefx,seanshpark/corefx,yizhang82/corefx,weltkante/corefx,twsouthwick/corefx,fgreinacher/corefx,JosephTremoulet/corefx,ptoonen/corefx,shmao/corefx,Jiayili1/corefx,mazong1123/corefx,dhoehna/corefx,Priya91/corefx-1,lggomez/corefx,alphonsekurian/corefx,cartermp/corefx,DnlHarvey/corefx,SGuyGe/corefx,billwert/corefx,seanshpark/corefx,shahid-pk/corefx,weltkante/corefx,MaggieTsang/corefx,billwert/corefx,Petermarcu/corefx,Priya91/corefx-1,Priya91/corefx-1,dotnet-bot/corefx,parjong/corefx,cydhaselton/corefx,krk/corefx,seanshpark/corefx,fgreinacher/corefx,lggomez/corefx,dotnet-bot/corefx,cydhaselton/corefx,alphonsekurian/corefx,SGuyGe/corefx,YoupHulsebos/corefx,jhendrixMSFT/corefx,stephenmichaelf/corefx,richlander/corefx,jlin177/corefx,weltkante/corefx,tstringer/corefx,Jiayili1/corefx,yizhang82/corefx,rjxby/corefx,alexperovich/corefx,the-dwyer/corefx,shahid-pk/corefx,shmao/corefx,nchikanov/corefx,mmitche/corefx,nchikanov/corefx,Chrisboh/corefx,tijoytom/corefx,twsouthwick/corefx,manu-silicon/corefx,iamjasonp/corefx,DnlHarvey/corefx,billwert/corefx,axelheer/corefx,stephenmichaelf/corefx,cydhaselton/corefx,axelheer/corefx,alphonsekurian/corefx,lggomez/corefx,ravimeda/corefx,Ermiar/corefx,shahid-pk/corefx,shmao/corefx,khdang/corefx,manu-silicon/corefx,ellismg/corefx,DnlHarvey/corefx,zhenlan/corefx,yizhang82/corefx,ViktorHofer/corefx,ViktorHofer/corefx,krytarowski/corefx,krytarowski/corefx,gkhanna79/corefx,JosephTremoulet/corefx,iamjasonp/corefx,Petermarcu/corefx,BrennanConroy/corefx,jhendrixMSFT/corefx,marksmeltzer/corefx,shimingsg/corefx,stone-li/corefx,ericstj/corefx,ravimeda/corefx,jlin177/corefx,rubo/corefx,ravimeda/corefx,nchikanov/corefx,parjong/corefx,gkhanna79/corefx,tijoytom/corefx,mazong1123/corefx,elijah6/corefx,dhoehna/corefx,ptoonen/corefx,richlander/corefx,jlin177/corefx,yizhang82/corefx,Petermarcu/corefx,alphonsekurian/corefx,Chrisboh/corefx,rjxby/corefx,krk/corefx,ViktorHofer/corefx,Jiayili1/corefx,adamralph/corefx,the-dwyer/corefx,krk/corefx,rjxby/corefx,weltkante/corefx,SGuyGe/corefx,stephenmichaelf/corefx,Jiayili1/corefx,Priya91/corefx-1,stephenmichaelf/corefx,parjong/corefx,marksmeltzer/corefx,zhenlan/corefx,dhoehna/corefx,marksmeltzer/corefx,tstringer/corefx,the-dwyer/corefx,manu-silicon/corefx,adamralph/corefx,weltkante/corefx,seanshpark/corefx,cartermp/corefx,khdang/corefx,krk/corefx,rjxby/corefx,rubo/corefx,billwert/corefx,twsouthwick/corefx,jhendrixMSFT/corefx,tstringer/corefx,alexperovich/corefx,mmitche/corefx,gkhanna79/corefx,gkhanna79/corefx,nchikanov/corefx,YoupHulsebos/corefx,Petermarcu/corefx,Jiayili1/corefx,ellismg/corefx,seanshpark/corefx,krytarowski/corefx,axelheer/corefx,tijoytom/corefx,nbarbettini/corefx,Priya91/corefx-1,dhoehna/corefx,shmao/corefx,Petermarcu/corefx,ViktorHofer/corefx,cartermp/corefx,YoupHulsebos/corefx,rjxby/corefx,parjong/corefx,tstringer/corefx,cydhaselton/corefx,nbarbettini/corefx,nbarbettini/corefx,Chrisboh/corefx,dotnet-bot/corefx,elijah6/corefx,the-dwyer/corefx,stone-li/corefx,MaggieTsang/corefx,mazong1123/corefx,Ermiar/corefx,iamjasonp/corefx,tijoytom/corefx,rubo/corefx,billwert/corefx,shimingsg/corefx,BrennanConroy/corefx,tijoytom/corefx,ericstj/corefx,alphonsekurian/corefx,shmao/corefx,DnlHarvey/corefx,ViktorHofer/corefx,rahku/corefx,nchikanov/corefx,Chrisboh/corefx,MaggieTsang/corefx,stone-li/corefx,mmitche/corefx,zhenlan/corefx,ellismg/corefx,YoupHulsebos/corefx,krk/corefx,dhoehna/corefx,rahku/corefx,yizhang82/corefx,rahku/corefx,rubo/corefx,the-dwyer/corefx,Ermiar/corefx,alexperovich/corefx,Petermarcu/corefx,shimingsg/corefx,ericstj/corefx,lggomez/corefx,shahid-pk/corefx,ptoonen/corefx,rjxby/corefx,wtgodbe/corefx,MaggieTsang/corefx,marksmeltzer/corefx,gkhanna79/corefx,dhoehna/corefx,weltkante/corefx,ptoonen/corefx,jhendrixMSFT/corefx,parjong/corefx,iamjasonp/corefx,stone-li/corefx,cydhaselton/corefx,manu-silicon/corefx,DnlHarvey/corefx,cartermp/corefx,parjong/corefx,ravimeda/corefx,tstringer/corefx,dotnet-bot/corefx,tijoytom/corefx,jlin177/corefx,gkhanna79/corefx,ericstj/corefx,mazong1123/corefx,DnlHarvey/corefx,richlander/corefx,the-dwyer/corefx,SGuyGe/corefx,krytarowski/corefx,nbarbettini/corefx,mmitche/corefx,shimingsg/corefx,wtgodbe/corefx,twsouthwick/corefx,krk/corefx,ericstj/corefx,stephenmichaelf/corefx,gkhanna79/corefx,YoupHulsebos/corefx,dsplaisted/corefx,yizhang82/corefx,mazong1123/corefx,ravimeda/corefx,richlander/corefx,nbarbettini/corefx,Ermiar/corefx,Chrisboh/corefx,JosephTremoulet/corefx,stephenmichaelf/corefx,lggomez/corefx,jlin177/corefx,shimingsg/corefx,marksmeltzer/corefx,iamjasonp/corefx,nbarbettini/corefx,rjxby/corefx,rahku/corefx,marksmeltzer/corefx,iamjasonp/corefx,lggomez/corefx,khdang/corefx,mmitche/corefx,elijah6/corefx,ravimeda/corefx,Jiayili1/corefx,rahku/corefx,DnlHarvey/corefx,tstringer/corefx,SGuyGe/corefx,ellismg/corefx,fgreinacher/corefx,wtgodbe/corefx,mmitche/corefx,cartermp/corefx,jlin177/corefx,khdang/corefx,parjong/corefx,jhendrixMSFT/corefx,ellismg/corefx,YoupHulsebos/corefx,zhenlan/corefx,shahid-pk/corefx,adamralph/corefx,rubo/corefx,dhoehna/corefx,wtgodbe/corefx,alphonsekurian/corefx,MaggieTsang/corefx,alexperovich/corefx,Priya91/corefx-1,rahku/corefx,manu-silicon/corefx,axelheer/corefx,richlander/corefx,the-dwyer/corefx,MaggieTsang/corefx,richlander/corefx,krytarowski/corefx,stone-li/corefx