protect: when unprotected, show old protections and their duration

[NovemLinguae]

Requested by Discospinster at https://en.wikipedia.org/wiki/Wikipedia_talk:Twinkle#Request%3A_Last_protection_duration_in_dialogue_box%3F

Currently, in the admin protect (PP) module, Twinkle will display that a current protection is in place and who placed it.

If there is no protection in place, Twinkle will not display details about the old protection. Twinkle will also not display the old protection duration. The old protection duration is useful info when deciding how long to reprotect for.

This ticket is to add old protection duration to the red info displayed when visiting the admin protect module.