[LYN-2522] Gem catalog header widgets (#919)

* Added header widget with the name based filter
* Added column title header together with the the number of currently shown/filtered gems

Code/Tools/ProjectManager/Source/GemCatalog/GemCatalogHeaderWidget.h

@@ -0,0 +1,31 @@
+/*
+* All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
+* its licensors.
+*
+* For complete copyright and license terms please see the LICENSE at the root of this
+* distribution (the "License"). All use of this software is governed by the License,
+* or, if provided, by the license below or the license accompanying this file. Do not
+* remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+*
+*/
+
+#pragma once
+
+#if !defined(Q_MOC_RUN)
+#include <GemCatalog/GemSortFilterProxyModel.h>
+#include <QFrame>
+#endif
+
+namespace O3DE::ProjectManager
+{
+    class GemCatalogHeaderWidget
+        : public QFrame
+    {
+        Q_OBJECT // AUTOMOC
+
+    public:
+        explicit GemCatalogHeaderWidget(GemSortFilterProxyModel* filterProxyModel, QWidget* parent = nullptr);
+        ~GemCatalogHeaderWidget() = default;
+    };
+} // namespace O3DE::ProjectManager