Fix URI template derivation and lookup (#530)

* Use lowercase host in resource URI template derivation.

* Address feedback

* Add casing testing for non-templated resource lookups.

* Fix uri primitive lookup

* Use a hardcoded mcp hostname in derived resource template URIs and ensure built-in resources work with the VS Code client.

* Address feedback

* Fix equality comparison

* Use dedicated type for resource collections.

samples/AspNetCoreSseServer/Program.cs

@@ -2,12 +2,14 @@ using OpenTelemetry;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Trace;
 using TestServerWithHosting.Tools;
+using TestServerWithHosting.Resources;
 
 var builder = WebApplication.CreateBuilder(args);
 builder.Services.AddMcpServer()
     .WithHttpTransport()
     .WithTools<EchoTool>()
-    .WithTools<SampleLlmTool>();
+    .WithTools<SampleLlmTool>()
+    .WithResources<SimpleResourceType>();
 
 builder.Services.AddOpenTelemetry()
     .WithTracing(b => b.AddSource("*")