[INSPECTOR] Never destroy RemoteInspectorHTTPServer singleton

Destroying RemoteInspectorHTTPServer with on different thread that
it was created on causes RELEASE_ASSERT to be triggered
(via ~RemoteInspectorClient -> ~TimerBase).

Such case happens when main UIProcess loop doesn't run in the main thread
(like WPE WebKitBrowser plugin scenario)

Author: asurdej-comcast

Source/WebKit/UIProcess/Inspector/glib/RemoteInspectorHTTPServer.cpp

@@ -31,14 +31,15 @@
 #include "RemoteInspectorClient.h"
 #include <WebCore/SoupVersioning.h>
 #include <wtf/FileSystem.h>
+#include <wtf/NeverDestroyed.h>
 #include <wtf/URL.h>
 #include <wtf/glib/GUniquePtr.h>
 
 namespace WebKit {
 
 RemoteInspectorHTTPServer& RemoteInspectorHTTPServer::singleton()
 {
-    static RemoteInspectorHTTPServer server;
+    static NeverDestroyed<RemoteInspectorHTTPServer> server;
     return server;
 }