Add wait time to loans page

https://openlibrary.org/account/loans
This helps a person know how long they'll wait until a book is available, which is really valuable to know. Without this knowledge - people might unfortunately miss their waitlist spot - which means they may wait for nothing - which isn't good. Or, because of not knowing when they'll be next on the waitlist, they don't check frequently enough that they hold others up - by staying on the waitlist when it becomes available instead of checking out the book - which holds up the line for others. My solution prevents all that.

Start at the loans page URL and inspect the existing waitlist information alongside the attached screenshot. Determine where the page gets loan status data, then add a visible estimate of how long a waiting user must wait; done means the wait time is shown accurately on the loans page.

Written by the indexing model from the issue text.