Feat: opus metadata encoding (#12974)

Feat: Downloading: Add opus audio metadata tags for title, author, date, and a comment tag with the originating URL

This removes the DownloadManagerService.EXTRA_SOURCE field, which is always inferred from the StreamInfo.

app/src/main/java/us/shandian/giga/postprocessing/OggFromWebmDemuxer.java

@@ -34,7 +34,7 @@ class OggFromWebmDemuxer extends Postprocessing {
 
     @Override
     int process(SharpStream out, @NonNull SharpStream... sources) throws IOException {
-        OggFromWebMWriter demuxer = new OggFromWebMWriter(sources[0], out);
+        OggFromWebMWriter demuxer = new OggFromWebMWriter(sources[0], out, streamInfo);
         demuxer.parseSource();
         demuxer.selectTrack(0);
         demuxer.build();