Add format place holder for album_type

This commit exposes the album type as a configuration placeholder.

Fixes #595

Change-Id: Ife8832534861fc01da5d68c37be6c7476a6a6964

tidal_dl_ng/helper/path.py

@@ -452,6 +452,11 @@ def _format_metadata(
         name == "album_explicit" and isinstance(media, Album)
     ):
         return FORMAT_TEMPLATE_EXPLICIT if media.explicit else ""
+    elif name == "media_type":
+        if isinstance(media, Album):
+            return media.type
+        elif isinstance(media, Track):
+            return media.album.type
     return None