Add an option to omit annotation of hidden categories

In case a category is marked as "hidden", option [0] can be used to omit
its annotation.

Pages that involve a hidden category need to be refreshed to ensure that
the StoreUpdater can make use of this information.

[0] $smwgShowHiddenCategories (default = true, legacy behaviour)

[1] https://www.mediawiki.org/wiki/Help:Categories#Hidden_categories

Bug: 54867
Change-Id: Ie3840872beee10cf96b0a311ba2dbd960bc7fb93