Make util function for Thread duration with fallbacks

[Pierre-Demessence]

When we make a thread we can specify the ThreadArchiveDuration. 1h, 1 day, 3 days and 7 days.
Above 1 day you need a server with a boost level (PremiumTier) of 1 or more.

To make thing more easy when dealing with thread, it could be good to have an util function that takes a "wanted duration" and returns the maximum possible duration if we can't have the wanted duration.