Engine settings UX update and basic functionality

Code/Tools/ProjectManager/Source/PathValidator.h

@@ -0,0 +1,45 @@
+/*
+* 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 <QValidator>
+#endif
+
+QT_FORWARD_DECLARE_CLASS(QWidget)
+
+namespace O3DE::ProjectManager
+{
+    class PathValidator 
+        : public QValidator
+    {
+    public:
+        enum class PathMode {
+            ExistingFile,   //!< A single, existings file. Useful for "Open file"
+            ExistingFolder, //!< A single, existing directory. Useful for "Open Folder"
+            AnyFile         //!< A single, valid file, doesn't have to exist but the directory must.  Useful for "Save File"
+        };
+
+        explicit PathValidator(PathMode pathMode, QWidget* parent = nullptr);
+        ~PathValidator() = default;
+
+        void setAllowEmpty(bool allowEmpty);
+        void setPathMode(PathMode pathMode);
+
+        QValidator::State validate(QString &text, int &) const override;
+
+    private:
+        PathMode m_pathMode = PathMode::AnyFile;
+        bool m_allowEmpty = false;
+    };
+} // namespace O3DE::ProjectManager