Group service/billing codes under categories in Whitespace

Summary

Allow service codes to be grouped under a parent category within the Whitespace view, so users can see coverage and gaps per category rather than only per individual service code.

Request

Enable grouping of service/billing codes under a parent category in Whitespace. The existing primary category structure would be the logical place to hook this in, as it already exists and customers are familiar with it. The view should then show, per customer, which categories have been sold into and which haven't, with the ability to drill down into the underlying service codes.

Value

Makes Whitespace usable for MSPs with large service catalogs, and aligns the sales view with how they actually talk about and sell their services.