Add a new non-TLS endpoint to the gRPC template

[shirhatti]

The only endpoint in the gRPC template is a TLS-enabled endpoint. As part of our desire for a better experience on macOS which doesn't have server-side ALPN and ergo HTTP/2 over TLS, we should add another endpoint to the template.

This in conjunction with grpc/grpc-dotnet#782 should greatly improve the experience on macOS.

cc @JamesNK

[blowdart]

Umm

https://grpc.io/docs/guides/auth/

Google will not allow connections without SSL/TLS, and most gRPC language implementations will not let you send credentials on an unencrypted channel.

If you do this you must be clear this is super unsupported and out of compliance.

[JamesNK]

We have a big warning for macOS situation - https://docs.microsoft.com/en-us/aspnet/core/grpc/troubleshoot?view=aspnetcore-3.1#unable-to-start-aspnet-core-grpc-app-on-macos

But, it occurs to me that there might be a side effect of this change. macOS devs no longer get an error like they did previously (I think? Worth checking), so are less likely to visit this troubleshooting page and see the warning.

[shirhatti]

Google will not allow connections without SSL/TLS, and most gRPC language implementations will not let you send credentials on an unencrypted channel.

Neither do we.

https://github.com/grpc/grpc-dotnet/blob/db7d128f59e52dc7430740fdeb9acb30e0b0fa64/src/Grpc.Net.Client/Internal/GrpcCall.cs#L711-L736