Use string.Create in BitConverter.ToString(byte[]) (dotnet/coreclr#15218)
Use string.Create in BitConverter.ToString(byte[]) (dotnet/coreclr#15218)

Avoids unnecessary allocations and copying, and reduces the amount of unsafe code.

Signed-off-by: dotnet-bot-corefx-mirror <03c4cb6107ae99956a7681f2c97ff7104809a2bd@microsoft.com>

zhenlan/corefx,ViktorHofer/corefx,BrennanConroy/corefx,ericstj/corefx,ericstj/corefx,Jiayili1/corefx,shimingsg/corefx,zhenlan/corefx,Jiayili1/corefx,ptoonen/corefx,Jiayili1/corefx,shimingsg/corefx,Jiayili1/corefx,ptoonen/corefx,shimingsg/corefx,wtgodbe/corefx,Jiayili1/corefx,shimingsg/corefx,ptoonen/corefx,ericstj/corefx,Ermiar/corefx,ravimeda/corefx,shimingsg/corefx,Jiayili1/corefx,wtgodbe/corefx,ravimeda/corefx,zhenlan/corefx,Ermiar/corefx,mmitche/corefx,ericstj/corefx,Ermiar/corefx,ViktorHofer/corefx,zhenlan/corefx,ericstj/corefx,mmitche/corefx,wtgodbe/corefx,ViktorHofer/corefx,ptoonen/corefx,shimingsg/corefx,ViktorHofer/corefx,zhenlan/corefx,ericstj/corefx,ViktorHofer/corefx,mmitche/corefx,wtgodbe/corefx,wtgodbe/corefx,ravimeda/corefx,mmitche/corefx,ptoonen/corefx,ViktorHofer/corefx,Jiayili1/corefx,zhenlan/corefx,BrennanConroy/corefx,ericstj/corefx,Ermiar/corefx,BrennanConroy/corefx,ptoonen/corefx,mmitche/corefx,wtgodbe/corefx,Ermiar/corefx,mmitche/corefx,ravimeda/corefx,ravimeda/corefx,ptoonen/corefx,Ermiar/corefx,ravimeda/corefx,Ermiar/corefx,mmitche/corefx,zhenlan/corefx,shimingsg/corefx,ravimeda/corefx,wtgodbe/corefx,ViktorHofer/corefx