[FEATURE] Create "Accesories" category

[hasecilu]

Is your feature request related to a problem? Please describe.
Currently the Addon Manager categorize addons as: workbenches, macros and preference packs but there are some "workbenches" that are not really workbenches as PieMenu that is more like a accessory. I think there are some UI-related addons that also fall on this category.

Describe the solution you'd like
Create an "Accessories" category to fit these kind of addons.

Describe alternatives you've considered
Create a misc category.

Additional context
Check this comment:　Grubuntu/PieMenu#63 (comment)

[luzpaz]

@chennes i think this makes sense.

Note: we would need to mention this in the Addon Manager documentation, I imagine.