Rationalize Aggregatable Properties, Dynamic Aggregates, and floating aggregates

In the CSD01 specification we sometimes treat properties as aggregates by applying a "default aggregation method". This was confusing to folks who didn't expect this special aggregation behavior to automatically apply to properties. other times the user can apply an aggregation method to a property or expression. In some cases an alias was required, in others it was not, and the type could be dependent on whether or not an alias was used.

The addition of floating aggregates added yet a new way to apply define aggregates, leaving services multiple ways to do the same thing and clients either having to support all different combinations or pick a subset of combinations and not be interoperable.

Also, we could use this opportunity to refactor the annotations so they are not nested under one huge annotation but are more naturally specified in the context which they apply.