Refactor extractor

- Refactor info classes and extractors
- Reformat and fix indentation
- Organize packages and classes
- Rename variables/methods and fix regex
- Change the capitalization
- Add methods to playlist extractor

services/youtube/YoutubePlaylistUrlIdHandler.java

@@ -0,0 +1,37 @@
+package org.schabi.newpipe.extractor.services.youtube;
+
+
+import org.schabi.newpipe.extractor.UrlIdHandler;
+import org.schabi.newpipe.extractor.exceptions.ParsingException;
+import org.schabi.newpipe.extractor.utils.Parser;
+
+public class YoutubePlaylistUrlIdHandler implements UrlIdHandler {
+
+    private static final String ID_PATTERN = "([\\-a-zA-Z0-9_]{34})";
+
+    @Override
+    public String getUrl(String listId) {
+        return "https://www.youtube.com/playlist?list=" + listId;
+    }
+
+    @Override
+    public String getId(String url) throws ParsingException {
+        try {
+            return Parser.matchGroup1("list=" + ID_PATTERN, url);
+        } catch (final Exception exception) {
+            throw new ParsingException("Error could not parse url :" + exception.getMessage(), exception);
+        }
+    }
+
+    @Override
+    public String cleanUrl(String complexUrl) throws ParsingException {
+        return getUrl(getId(complexUrl));
+    }
+
+    @Override
+    public boolean acceptUrl(String videoUrl) {
+        final boolean hasNotEmptyUrl = videoUrl != null && !videoUrl.isEmpty();
+        final boolean isYoutubeDomain = hasNotEmptyUrl && (videoUrl.contains("youtube") || videoUrl.contains("youtu.be"));
+        return isYoutubeDomain && videoUrl.contains("list=");
+    }
+}