Add a category of lazy attributes in dataset builders.

### Feature Description

Currently variable_max_size attribute is loaded only if required by a rule. Extend this functionality to allow specifying a list of attributes to check if they are needed. This will allow to load some "expensive" attributes only for rules, which actually require them (like variable_has_empty_values, variable_is_empty).

Start by locating the dataset builders and tracing how variable_max_size is currently loaded only when required by a rule. Identify the rule handling for variable_has_empty_values and variable_is_empty, then determine how a configurable list of lazy attributes should be checked. Done means expensive attributes are loaded only for rules that require them without changing existing variable_max_size behavior.

Written by the indexing model from the issue text.