[Move refactor] Move dialogs to interface/widgets/ (#6234)

* Move dialogs/ underneath interface/widgets since QDialog inherits from QWidget.

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

cockatrice/src/interface/widgets/dialogs/dlg_load_deck.h

@@ -0,0 +1,27 @@
+/**
+ * @file dlg_load_deck.h
+ * @ingroup LocalDeckStorageDialogs
+ * @ingroup Lobby
+ * @brief TODO: Document this.
+ */
+
+#ifndef DLG_LOAD_DECK_H
+#define DLG_LOAD_DECK_H
+
+#include <QFileDialog>
+
+/**
+ * The file dialog for "Load Deck" operations.
+ * Handles remembering the most recently used deck loading directory.
+ */
+class DlgLoadDeck : public QFileDialog
+{
+    Q_OBJECT
+
+    void actAccepted();
+
+public:
+    explicit DlgLoadDeck(QWidget *parent = nullptr);
+};
+
+#endif // DLG_LOAD_DECK_H