Support detectEncodingFromByteOrderMark in OpenRead
Support detectEncodingFromByteOrderMark in OpenRead

This method is a compat layer to make moving to .NET Core easier, but it
was missing one of the constructor's arguments.  Added it with the default
that matches the XmlTextReader behavior in the absence of the argument.

jeffkl/msbuild,chipitsine/msbuild,cdmihai/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild,Microsoft/msbuild,chipitsine/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,AndyGerlicher/msbuild,jeffkl/msbuild,mono/msbuild,rainersigwald/msbuild,AndyGerlicher/msbuild,cdmihai/msbuild,chipitsine/msbuild,jeffkl/msbuild,Microsoft/msbuild,rainersigwald/msbuild,cdmihai/msbuild,rainersigwald/msbuild,mono/msbuild,mono/msbuild,Microsoft/msbuild,Microsoft/msbuild,mono/msbuild,cdmihai/msbuild,sean-gilliam/msbuild,jeffkl/msbuild,chipitsine/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild