[YouTube] Add support for automatic dubbed and secondary tracks

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeParsingHelper.java

@@ -1720,9 +1720,12 @@ public final class YoutubeParsingHelper {
             case "original":
                 return AudioTrackType.ORIGINAL;
             case "dubbed":
+            case "dubbed-auto":
                 return AudioTrackType.DUBBED;
             case "descriptive":
                 return AudioTrackType.DESCRIPTIVE;
+            case "secondary":
+                return AudioTrackType.SECONDARY;
             default:
                 return null;
         }

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/dashmanifestcreators/YoutubeDashManifestCreatorsUtils.java

@@ -325,6 +325,8 @@ public final class YoutubeDashManifestCreatorsUtils {
                 case DESCRIPTIVE:
                     return "description";
                 default:
+                    // Secondary track types do not seem to have a dedicated role in the DASH
+                    // specification, so use alternate for them
                     return "alternate";
             }
         }

extractor/src/main/java/org/schabi/newpipe/extractor/stream/AudioTrackType.java

@@ -1,12 +1,13 @@
 package org.schabi.newpipe.extractor.stream;
 
 /**
- * An enum representing the track type of an {@link AudioStream} extracted by a {@link
+ * An enum representing the track type of {@link AudioStream}s extracted by a {@link
  * StreamExtractor}.
  */
 public enum AudioTrackType {
+
     /**
-     * An original audio track of the video.
+     * An original audio track of a video.
      */
     ORIGINAL,
 
@@ -20,6 +21,7 @@ public enum AudioTrackType {
 
     /**
      * A descriptive audio track.
+     *
      * <p>
      * A descriptive audio track is an audio track in which descriptions of visual elements of
      * a video are added to the original audio, with the goal to make a video more accessible to
@@ -29,5 +31,15 @@ public enum AudioTrackType {
      * @see <a href="https://en.wikipedia.org/wiki/Audio_description">
      * https://en.wikipedia.org/wiki/Audio_description</a>
      */
-    DESCRIPTIVE
+    DESCRIPTIVE,
+
+    /**
+     * A secondary audio track.
+     *
+     * <p>
+     * A secondary audio track can be an alternate audio track from the original language of a
+     * video or an alternate language.
+     * </p>
+     */
+    SECONDARY
 }