Fix subscription picker items flickering in the feed group dialog

The adapter could not tell the items were the same because the
subscription class was missing some methods (i.e. equals and hashcode),
so a full rebind was being done.

app/src/main/java/org/schabi/newpipe/database/subscription/SubscriptionEntity.java

@@ -130,4 +130,55 @@ public class SubscriptionEntity {
         item.setDescription(getDescription());
         return item;
     }
+
+
+    // TODO: Remove these generated methods by migrating this class to a data class from Kotlin.
+    @Override
+    @SuppressWarnings("EqualsReplaceableByObjectsCall")
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        final SubscriptionEntity that = (SubscriptionEntity) o;
+
+        if (uid != that.uid) {
+            return false;
+        }
+        if (serviceId != that.serviceId) {
+            return false;
+        }
+        if (!url.equals(that.url)) {
+            return false;
+        }
+        if (name != null ? !name.equals(that.name) : that.name != null) {
+            return false;
+        }
+        if (avatarUrl != null ? !avatarUrl.equals(that.avatarUrl) : that.avatarUrl != null) {
+            return false;
+        }
+        if (subscriberCount != null
+                ? !subscriberCount.equals(that.subscriberCount)
+                : that.subscriberCount != null) {
+            return false;
+        }
+        return description != null
+                ? description.equals(that.description)
+                : that.description == null;
+    }
+
+    @Override
+    public int hashCode() {
+        int result = (int) (uid ^ (uid >>> 32));
+        result = 31 * result + serviceId;
+        result = 31 * result + url.hashCode();
+        result = 31 * result + (name != null ? name.hashCode() : 0);
+        result = 31 * result + (avatarUrl != null ? avatarUrl.hashCode() : 0);
+        result = 31 * result + (subscriberCount != null ? subscriberCount.hashCode() : 0);
+        result = 31 * result + (description != null ? description.hashCode() : 0);
+        return result;
+    }
 }