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/LibHTML/CSS/Selector.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <AK/AKString.h>
+#include <AK/Vector.h>
+#include <LibHTML/CSS/Specificity.h>
+
+class Selector {
+public:
+    struct Component {
+        enum class Type {
+            Invalid,
+            TagName,
+            Id,
+            Class
+        };
+        Type type { Type::Invalid };
+        String value;
+    };
+
+    explicit Selector(Vector<Component>&&);
+    ~Selector();
+
+    const Vector<Component>& components() const { return m_components; }
+
+    Specificity specificity() const;
+
+private:
+    Vector<Component> m_components;
+};