Added AllowClientSslRenegotiation property on .NET STANDARD 2.1

[eallegretta]

.NET 7 made AllowRenegotiation on SslStream false by default to avoid the following potential vulnerability https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3555, I've added a setting to make it true in the event someone wants to set it, this only applies to .NET STANDARD 2.1, support for netstandard2.1 target framework has also been added