[DeckLoader] Extract LoadedDeck struct (#6406)

* [DeckLoader] Extract LoadedDeck struct

* update usages

* Move enum to separate namespace

* format

* format

* format

cockatrice/src/interface/deck_loader/deck_file_format.h

@@ -0,0 +1,36 @@
+#ifndef COCKATRICE_DECK_FILE_FORMAT_H
+#define COCKATRICE_DECK_FILE_FORMAT_H
+#include <QString>
+
+namespace DeckFileFormat
+{
+
+/**
+ * The deck file formats that Cockatrice supports.
+ */
+enum Format
+{
+    /**
+     * Plaintext deck files, a format that is intended to be widely supported among different programs.
+     * This format does not support Cockatrice specific features such as banner cards or tags.
+     */
+    PlainText,
+
+    /**
+     * This is cockatrice's native deck file format, and supports deck metadata such as banner cards and tags.
+     * Stored as .cod files.
+     */
+    Cockatrice
+};
+
+/**
+ * Determines what deck file format the given filename corresponds to.
+ *
+ * @param fileName The filename
+ * @return The deck format
+ */
+Format getFormatFromName(const QString &fileName);
+
+} // namespace DeckFileFormat
+
+#endif // COCKATRICE_DECK_FILE_FORMAT_H