Fixed IServer.Hang command in RedisServer. Database number is not nee…

Replace usage of SpinWait struct with simple increment operation.  SpinWait.SpinOnce() takes too much time than the original Thread.SpinWait(5).

Add Transaction Conditions for List Index

Update moq.netcore to 4.4.0.  The old version didn't specify its dependencies for the 'dotnet' group.

Trace IOException for stream.Read(). Otherwise the IO exception would be wrapped in an AggregateException, which would not be caught by the try-catch around BeginRead() method call.

Also unwrap AggregateException in EndRead() and re-throw its inner exception.

Use Volatile wrapper.

Merge branch 'UpdateNUnitTo3' of https://github.com/RogerBestMsft/StackExchange.Redis into netcore-test