Include inheritors from other modules in the inheritors tab

[mkrussel77]

Is your feature request related to a problem? Please describe
Currently the inheritor tab only shows subclasses in the same module. It is often helpful to see all the inheritors from all modules in a multimodule project.

Describe the solution you'd like
Like the multi module task version of the HTML format to find inheritors in other dependent modules and merge them into the list of inheritors from the partial task.