asfdata does not support nested data items

asfdata needs to return data in a form suitable for use by ezt, which only supports nested entries as attributes.

Items that are dicts need to be converted into a class with entries as attributes.

So a.b['c'] (not supported by ezt) can be accessed as a.b.c (which is).

Locate the asfdata implementation and any existing tests, then read how it currently handles dictionary-valued items and how ezt consumes the returned data. Implement the conversion of nested dictionaries into attribute-accessible objects, and verify that nested values are available through dotted access while existing data handling remains intact.

Written by the indexing model from the issue text.