KRA/ORA: merged in a single plugin and added metadata support

- ORA/KRA: merged in a single plugin (KRA)
- ORA: removed standalone plugin
- KRA: use of logging category
- KRA: add metadata support by processing the embedded `documentinfo.xml`
- Improved signature lookup (see MR !17) and added test case

src/imageformats/kra_p.h

@@ -0,0 +1,34 @@
+/*
+    This file is part of the KDE project
+    SPDX-FileCopyrightText: 2013 Boudewijn Rempt <[email protected]>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+#ifndef KIMG_KRA_H
+#define KIMG_KRA_H
+
+#include <QImageIOPlugin>
+
+class KraHandler : public QImageIOHandler
+{
+public:
+    KraHandler();
+
+    bool canRead() const override;
+    bool read(QImage *image) override;
+
+    static bool canRead(QIODevice *device);
+};
+
+class KraPlugin : public QImageIOPlugin
+{
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QImageIOHandlerFactoryInterface" FILE "kra.json")
+
+public:
+    Capabilities capabilities(QIODevice *device, const QByteArray &format) const override;
+    QImageIOHandler *create(QIODevice *device, const QByteArray &format = QByteArray()) const override;
+};
+
+#endif