PROD-I-828 Subscribe to linked content in bulk

The user uses the subscribe feature to know if they need to update content if something changes in one answer and then needs to be updated in a similar answer. For example, if the user has similar answers about how many languages we support that are linked. When he update one, he know to update the other one. Rather than having to click subscribe on every single answer that is linked, it would be nice to click a button that said something like "subscribe to all linked content" so the user gets all the updates. This saves time.