Fail on startup for Http/2 HTTPS on Mac #11061
Description
Mac doesn't support ALPN: https://github.com/dotnet/corefx/issues/33016
In 3.0 HTTPS and HTTP/2 (and HTTP/1) are enabled by default. The GRPC template is going to disable HTTP/1. HTTP/2 per spec requires ALPN when used over HTTPS. Today this fails per request and you have to dig into the server logs for the error.
Proposal: Check for HTTPS + HTTP/2-only on Mac at startup and fail early.