Libraries: Create top level directory for libraries.

Things were getting a little crowded in the project root, so this patch
moves the Lib*/ directories into Libraries/.

Libraries/LibCore/CNetworkJob.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <AK/Function.h>
+#include <LibCore/CObject.h>
+
+class CNetworkResponse;
+
+class CNetworkJob : public CObject {
+public:
+    enum class Error {
+        None,
+        ConnectionFailed,
+        TransmissionFailed,
+        ProtocolFailed,
+    };
+    virtual ~CNetworkJob() override;
+
+    Function<void(bool success)> on_finish;
+
+    bool has_error() const { return m_error != Error::None; }
+    Error error() const { return m_error; }
+    CNetworkResponse* response() { return m_response.ptr(); }
+    const CNetworkResponse* response() const { return m_response.ptr(); }
+
+    virtual void start() = 0;
+
+    virtual const char* class_name() const override { return "CNetworkJob"; }
+
+protected:
+    CNetworkJob();
+    void did_finish(NonnullRefPtr<CNetworkResponse>&&);
+    void did_fail(Error);
+
+private:
+    RefPtr<CNetworkResponse> m_response;
+    Error m_error { Error::None };
+};
+
+const char* to_string(CNetworkJob::Error);