This also fixes some code style errors.
This also include a performance increase in running phpcs, performance
increase was done by addshore :).
Change-Id: I74a3d3134791ac22c332bb4fa0bc5c3662599394
If a hidden category has a member added or removed
this will only be shown to users that have the user
preference "display hidden categories".
Also added method to WikiCategoryPage to check
for hidden status.
Added unit tests for both.
Bug: T127944
Change-Id: Ic53d51391fa29d5e18fef4c42b8a275816c7ba4a