Enable HTTP/3 datagram in the simple server when WebTransport is also enabled.

PiperOrigin-RevId: 367345101
Change-Id: Ibca76aedc34abc3afc4d9a339ad6d0d9c862082c

quic/tools/quic_simple_server_session.h

diff --git a/quic/tools/quic_simple_server_session.h b/quic/tools/quic_simple_server_session.h
index 5a91ed9..b91966d 100644
--- a/quic/tools/quic_simple_server_session.h
+++ b/quic/tools/quic_simple_server_session.h
@@ -107,6 +107,10 @@
   bool ShouldNegotiateWebTransport() override {
     return quic_simple_server_backend_->SupportsWebTransport();
   }
+  bool ShouldNegotiateHttp3Datagram() override {
+    return QuicServerSessionBase::ShouldNegotiateHttp3Datagram() ||
+           ShouldNegotiateWebTransport();
+  }
 
  private:
   friend class test::QuicSimpleServerSessionPeer;