Track coffer keys on each character left

From spotts on [CF](https://www.curseforge.com/wow/addons/weekly-rewards/comments#7895593):

> Firstly thankyou for this addon. I have all classes leveled and tracking is a pain. I like that the addon shows shards completed but is there ANY way to track coffer keys on each character left. The addons on curse that did this no longer are updated or work. I have to log on and write down that coffer keys on each toon and update manually. Thanks heaps. Np if this isn't possible.