HTTP and gRPC client factory extension method to make using named endpoints easier

[JamesNK]

Named endpoints design is ongoing, but one suggestion is to stash the name in the URL. Unfortunately, that makes the URL specified in user's apps rather ugly:

app.AddHttpClient<CatalogServiceClient>(c => c.BaseAddress = new("http://_http1.catalogservice"));
app.AddHttpClient<Greeter.GreetClient>(c => c.Address = new("http://_http2.catalogservice"));

A potential improvement is to add extension methods for HttpClientFactory and GrpcClientFactory that accepts address/name. The new methods would internally call AddHttpClient/AddGrpcClient and builds the ugly URL for the user:

app.AddHttpClient<CatalogServiceClient>(new("http://catalogservice"), name: "http1");
app.AddGrpcClient<Greeter.GreetClient>(new("http://catalogservice"), name: "http2");

[JamesNK]

Maybe: These methods internally call UseServiceDiscovery for the named client.

[davidfowl]

I'm assuming this shouldn't be app but a method hanging off IHttpClientBuilder. I'm not sure we want infinity overloads though.

[davidfowl]

Move this to post preview @danmoseley

[maddymontaquila]

We're closing this due to inactivity and also that we don't think we'll be ever prioritize - @JamesNK ping me and David if you want details LOL I do want this though