As a Watchlist Expiry user, I want to watch both the new and original page (when moved) for the specified amount of time, so that the behavior can match that of permanently watched pages during a move.

Background: When moving a page using the API and the new page is meant to be watched, but you don't provide an expiry, the new page is always watched indefinitely. It does not use the expiry of the old page, if one existed.

Acceptance Criteria:

• The new page should be watched for the same duration as the old page, unless a value is provided for watchlistexpiry