Write and WriteAsync overloads for StringBuilder. (dotnet/coreclr#18281)
Write and WriteAsync overloads for StringBuilder. (dotnet/coreclr#18281)

* Write and WriteAsync overloads for StringBuilder.

Addresses issue https://github.com/dotnet/corefx/issues/30048

Note that tests will come as a separate checking as part of the coreFX repo.

* Review feedback

* Review feedback

* Added WriteLine(StringBuilder overloads (review feedback)

* review feedback

* Fix configureAwait

* bug fix

* Bug fix

* review feedback

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

ViktorHofer/corefx,ptoonen/corefx,mmitche/corefx,ericstj/corefx,Jiayili1/corefx,ViktorHofer/corefx,shimingsg/corefx,wtgodbe/corefx,mmitche/corefx,mmitche/corefx,ptoonen/corefx,wtgodbe/corefx,ViktorHofer/corefx,ViktorHofer/corefx,ericstj/corefx,ptoonen/corefx,BrennanConroy/corefx,ptoonen/corefx,ViktorHofer/corefx,mmitche/corefx,ericstj/corefx,ericstj/corefx,ptoonen/corefx,shimingsg/corefx,Jiayili1/corefx,wtgodbe/corefx,ptoonen/corefx,Jiayili1/corefx,wtgodbe/corefx,shimingsg/corefx,ericstj/corefx,wtgodbe/corefx,BrennanConroy/corefx,shimingsg/corefx,wtgodbe/corefx,Jiayili1/corefx,ericstj/corefx,Jiayili1/corefx,mmitche/corefx,ViktorHofer/corefx,mmitche/corefx,Jiayili1/corefx,shimingsg/corefx,ericstj/corefx,shimingsg/corefx,wtgodbe/corefx,BrennanConroy/corefx,mmitche/corefx,ViktorHofer/corefx,shimingsg/corefx,ptoonen/corefx,Jiayili1/corefx