Missing patterns for Struct

[marcandre]

We need a struct_constructor? matcher (see #8122)
A more general "class_definition?matcher that would matchclass Foo < Bar, Struct.new(...) doandClass.new(...) do` would be nice too

[marcandre]

Maybe the same should be applied to Modules, and a very generic module_definition? that would encompass both classes (which are modules) and modules?

[bbatsov]

I like this idea, although we'll probably need something more specific for modules as well, as I don't recall many instances in RuboCop where we treated classes as modules.

[marcandre]

Right, I don't know the cops well enough, there might not be a need for a way to select "code blocks".