Categories created thanks to a given action

[Krho]

Mass-uploads, accreditations and other actions not only add lot of medias in Wikimedia Commons. They very often lead to a structuration of the project, through the creation of new categories.

We should
_ propose a property meaning that a category is created thanks to a given action ;
_ compute all the categories created thanks to a given action.

[PierreSelim]

@Krho @JeanFred is it finished ?

Just a global note: When creating a featured issue we should also focus on describing when the issue is considered finished.