[ntcore] Networking improvements

- Utilize TrySend to properly backpressure network traffic
- Split updates into reasonable sized frames using WS fragmentation
- Use WS pings for network aliveness (requires 4.1 protocol revision)
- Measure RTT only at start of connection, rather than periodically
  (this avoids them being affected by other network traffic)
- Refactor network queue
- Refactor network ping, ping from server as well
- Improve meta topic performance

This adds a new protocol version (4.1) due to WS bugs in prior versions.

ntcore/src/main/native/cpp/NetworkClient.cpp

@@ -369,30 +369,34 @@ void NetworkClient::TcpConnected(uv::Tcp& tcp) {
   wpi::SmallString<128> idBuf;
   auto ws = wpi::WebSocket::CreateClient(
       tcp, fmt::format("/nt/{}", wpi::EscapeURI(m_id, idBuf)), "",
-      {{"networktables.first.wpi.edu"}}, options);
+      {"v4.1.networktables.first.wpi.edu", "networktables.first.wpi.edu"},
+      options);
   ws->SetMaxMessageSize(kMaxMessageSize);
-  ws->open.connect([this, &tcp, ws = ws.get()](std::string_view) {
+  ws->open.connect([this, &tcp, ws = ws.get()](std::string_view protocol) {
     if (m_connList.IsConnected()) {
       ws->Terminate(1006, "no longer needed");
       return;
     }
-    WsConnected(*ws, tcp);
+    WsConnected(*ws, tcp, protocol);
   });
 }
 
-void NetworkClient::WsConnected(wpi::WebSocket& ws, uv::Tcp& tcp) {
+void NetworkClient::WsConnected(wpi::WebSocket& ws, uv::Tcp& tcp,
+                                std::string_view protocol) {
   if (m_parallelConnect) {
     m_parallelConnect->Succeeded(tcp);
   }
 
   ConnectionInfo connInfo;
   uv::AddrToName(tcp.GetPeer(), &connInfo.remote_ip, &connInfo.remote_port);
-  connInfo.protocol_version = 0x0400;
+  connInfo.protocol_version =
+      protocol == "v4.1.networktables.first.wpi.edu" ? 0x0401 : 0x0400;
 
   INFO("CONNECTED NT4 to {} port {}", connInfo.remote_ip, connInfo.remote_port);
   m_connHandle = m_connList.AddConnection(connInfo);
 
-  m_wire = std::make_shared<net::WebSocketConnection>(ws);
+  m_wire =
+      std::make_shared<net::WebSocketConnection>(ws, connInfo.protocol_version);
   m_clientImpl = std::make_unique<net::ClientImpl>(
       m_loop.Now().count(), m_inst, *m_wire, m_logger, m_timeSyncUpdated,
       [this](uint32_t repeatMs) {

ntcore/src/main/native/cpp/NetworkClient.h

@@ -138,7 +138,8 @@ class NetworkClient final : public NetworkClientBase {
  private:
   void HandleLocal();
   void TcpConnected(wpi::uv::Tcp& tcp) final;
-  void WsConnected(wpi::WebSocket& ws, wpi::uv::Tcp& tcp);
+  void WsConnected(wpi::WebSocket& ws, wpi::uv::Tcp& tcp,
+                   std::string_view protocol);
   void ForceDisconnect(std::string_view reason) override;
   void DoDisconnect(std::string_view reason) override;
 

ntcore/src/main/native/cpp/NetworkServer.cpp

@@ -82,7 +82,9 @@ class NetworkServer::ServerConnection4 final
                     std::string_view addr, unsigned int port,
                     wpi::Logger& logger)
       : ServerConnection{server, addr, port, logger},
-        HttpWebSocketServerConnection(stream, {"networktables.first.wpi.edu"}) {
+        HttpWebSocketServerConnection(stream,
+                                      {"v4.1.networktables.first.wpi.edu",
+                                       "networktables.first.wpi.edu"}) {
     m_info.protocol_version = 0x0400;
   }
 
@@ -228,8 +230,12 @@ void NetworkServer::ServerConnection4::ProcessWsUpgrade() {
 
   m_websocket->SetMaxMessageSize(kMaxMessageSize);
 
-  m_websocket->open.connect([this, name = std::string{name}](std::string_view) {
-    m_wire = std::make_shared<net::WebSocketConnection>(*m_websocket);
+  m_websocket->open.connect([this, name = std::string{name}](
+                                std::string_view protocol) {
+    m_info.protocol_version =
+        protocol == "v4.1.networktables.first.wpi.edu" ? 0x0401 : 0x0400;
+    m_wire = std::make_shared<net::WebSocketConnection>(
+        *m_websocket, m_info.protocol_version);
     // TODO: set local flag appropriately
     std::string dedupName;
     std::tie(dedupName, m_clientId) = m_server.m_serverImpl.AddClient(