feat(metadata): add UPC support for metadata tagging

This update introduces support for handling UPCs (Universal Product Codes) in metadata processing. It ensures that UPC information is extracted, stored, and written to the appropriate metadata tags for various formats.

- ✨ **Feature**: Adds UPC field to metadata handling.
- 🛠️ **Enhancement**: Updates metadata initialization to include UPC.
- 🗂️ **Tagging**: Implements UPC writing for supported file formats.
- ✅ **Compatibility**: Ensures proper handling when UPC is absent.

This improvement enhances metadata completeness and compatibility with systems requiring UPC data.

tidal_dl_ng/download.py

@@ -1211,6 +1211,7 @@ class Download:
             track_peak_amplitude=media_stream.track_peak_amplitude,
             url_share=track.share_url if track.share_url else "",
             replay_gain_write=self.settings.data.metadata_replay_gain,
+            upc=track.album.upc if track.album and track.album.upc else "",
         )
 
         m.save()