Add ForwardedRequestCustomizer (#3407)

This allows jetty to correctly handle x-forwarded-* headers.

```
$ curl -H "x-forwarded-proto: https" -H "x-forwarded-host: example.com" -I http://localhost:10000
HTTP/1.1 302 Found
Date: Mon, 06 Feb 2023 02:41:34 GMT
Location: https://example.com/ide/
Content-Length: 0
Server: Jetty(11.0.13)
```

server/jetty/src/main/java/io/deephaven/server/jetty/JettyBackedGrpcServer.java

@@ -23,6 +23,7 @@
 import org.eclipse.jetty.http2.server.HTTP2CServerConnectionFactory;
 import org.eclipse.jetty.http2.server.HTTP2ServerConnectionFactory;
 import org.eclipse.jetty.security.ConstraintSecurityHandler;
+import org.eclipse.jetty.server.ForwardedRequestCustomizer;
 import org.eclipse.jetty.server.HttpConfiguration;
 import org.eclipse.jetty.server.HttpConnectionFactory;
 import org.eclipse.jetty.server.SecureRequestCustomizer;
@@ -224,6 +225,7 @@ public int getPort() {
     private static ServerConnector createConnector(Server server, JettyConfig config) {
         // https://www.eclipse.org/jetty/documentation/jetty-11/programming-guide/index.html#pg-server-http-connector-protocol-http2-tls
         final HttpConfiguration httpConfig = new HttpConfiguration();
+        httpConfig.addCustomizer(new ForwardedRequestCustomizer());
         final HttpConnectionFactory http11 = config.http1OrDefault() ? new HttpConnectionFactory(httpConfig) : null;
         final ServerConnector serverConnector;
         if (config.ssl().isPresent()) {