Check whether it is possible to refine detection of package type

follow up on #91.
As discussed on #116 we should check whether it is possible to detect modules, based on the existence of a class implementing `ICakeModule` and/or the existence of a `CakeModule` attribute.

Review the context in issues #91 and #116, then locate the existing package-type detection logic in the repository. Determine whether module detection can use an ICakeModule implementation, a CakeModule attribute, or both, and document the resulting detection behavior and tests needed.

Written by the indexing model from the issue text.