Everywhere: Replace a bundle of dbg with dbgln.

These changes are arbitrarily divided into multiple commits to make it
easier to find potentially introduced bugs with git bisect.Everything:

The modifications in this commit were automatically made using the
following command:

    find . -name '*.cpp' -exec sed -i -E 's/dbg\(\) << ("[^"{]*");/dbgln\(\1\);/' {} \;

Libraries/LibHTTP/HttpJob.cpp

@@ -40,7 +40,7 @@ void HttpJob::start()
     m_socket = Core::TCPSocket::construct(this);
     m_socket->on_connected = [this] {
 #ifdef CHTTPJOB_DEBUG
-        dbg() << "HttpJob: on_connected callback";
+        dbgln("HttpJob: on_connected callback");
 #endif
         on_socket_connected();
     };