chore: Reorganize examples and interop crates (#180)

* chore: Reorganize examples and interop crates

* fix interop tests

interop/src/bin/server.rs

@@ -0,0 +1,70 @@
+use http::header::HeaderName;
+use structopt::StructOpt;
+use tonic::body::BoxBody;
+use tonic::client::GrpcService;
+use tonic::transport::Server;
+use tonic::transport::{Identity, ServerTlsConfig};
+use tonic_interop::{server, MergeTrailers};
+
+#[derive(StructOpt)]
+struct Opts {
+    #[structopt(long)]
+    use_tls: bool,
+}
+
+#[tokio::main]
+async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
+    tonic_interop::trace_init();
+
+    let matches = Opts::from_args();
+
+    let addr = "127.0.0.1:10000".parse().unwrap();
+
+    let mut builder = Server::builder().interceptor_fn(|svc, req| {
+        let echo_header = req
+            .headers()
+            .get("x-grpc-test-echo-initial")
+            .map(Clone::clone);
+
+        let echo_trailer = req
+            .headers()
+            .get("x-grpc-test-echo-trailing-bin")
+            .map(Clone::clone)
+            .map(|v| (HeaderName::from_static("x-grpc-test-echo-trailing-bin"), v));
+
+        let call = svc.call(req);
+
+        async move {
+            let mut res = call.await?;
+
+            if let Some(echo_header) = echo_header {
+                res.headers_mut()
+                    .insert("x-grpc-test-echo-initial", echo_header);
+            }
+
+            Ok(res
+                .map(|b| MergeTrailers::new(b, echo_trailer))
+                .map(BoxBody::new))
+        }
+    });
+
+    if matches.use_tls {
+        let cert = tokio::fs::read("interop/data/server1.pem").await?;
+        let key = tokio::fs::read("interop/data/server1.key").await?;
+        let identity = Identity::from_pem(cert, key);
+
+        builder = builder.tls_config(ServerTlsConfig::with_rustls().identity(identity));
+    }
+
+    let test_service = server::TestServiceServer::new(server::TestService::default());
+    let unimplemented_service =
+        server::UnimplementedServiceServer::new(server::UnimplementedService::default());
+
+    builder
+        .add_service(test_service)
+        .add_service(unimplemented_service)
+        .serve(addr)
+        .await?;
+
+    Ok(())
+}