network, web_service: Add Verification backend and use new lobby API

Added verify_backend to load user_data for members. and removed method to generate UID as this is now done server-side.

Added GetUsername function and a "token" param to room_member.
Also added a username to ChatEntry, so that the username can be shown (along with nicknames) in the chat dialog.

src/web_service/verify_user_jwt.h

@@ -0,0 +1,25 @@
+// Copyright 2018 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <fmt/format.h>
+#include "network/verify_user.h"
+#include "web_service/web_backend.h"
+
+namespace WebService {
+
+class VerifyUserJWT final : public Network::VerifyUser::Backend {
+public:
+    VerifyUserJWT(const std::string& host);
+    ~VerifyUserJWT() = default;
+
+    Network::VerifyUser::UserData LoadUserData(const std::string& verify_UID,
+                                               const std::string& token) override;
+
+private:
+    std::string pub_key;
+};
+
+} // namespace WebService