Migrate from Picasso to Coil

Based on changes from refactor

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>

app/src/main/java/org/schabi/newpipe/DownloaderImpl.java

@@ -48,6 +48,11 @@ public final class DownloaderImpl extends Downloader {
         this.mCookies = new HashMap<>();
     }
 
+    @NonNull
+    public OkHttpClient getClient() {
+        return client;
+    }
+
     /**
      * It's recommended to call exactly once in the entire lifetime of the application.
      *