Update headers in lobby

Some gloox headers need workarounds to be included, so mark the header
"lib/external_libraries/gloox.h" as source for all gloox symbols and
collect all headers we use under it.

Further make include-what-you-use happy with files in source/lobby and
fix what needs to be fixed after.

Ref: #8086
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>

source/lobby/scripting/GlooxScriptConversions.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -19,10 +19,17 @@
 
 #include "lib/config2.h"
 #if CONFIG2_LOBBY
+#include "lib/external_libraries/gloox.h"
 #include "lib/utf8.h"
 #include "lobby/XmppClient.h"
 #include "scriptinterface/ScriptConversions.h"
 
+#include <js/RootingAPI.h>
+#include <js/TypeDecls.h>
+#include <string>
+
+class ScriptRequest;
+
 template<> void Script::ToJSVal<gloox::Presence::PresenceType>(const ScriptRequest& rq, JS::MutableHandleValue ret, const gloox::Presence::PresenceType& val)
 {
 	ToJSVal(rq, ret, XmppClient::GetPresenceString(val));