grouping attributes in consent UI

[Cantor, Scott]

> I guess that the end goal is that the deployer "just" defines a few attributes
> with well known names and the Federation supplied information controls the
> rest (encoding, display, filtering and so on).

The basic idea is to provide a separate recipe for as many attributes and their metadata as possible, and then just "connect" up the attributes from the resolver with those definitions, either by assuming the IDs line up by convention or by just attaching the ID to the attribute in the resolver some how that's not confusing. I haven't really worked it out beyond the general idea that anything that's currently "inside" the <AttributeDefinition> element at the top level would be something we'd want to factor out.

-- Scott