Add implcit imports for modules defined by instantiation

[yav]

Consider the following example:

module M where

submodule A where
  x = 2

submodule F where
  parameter
    a: Integer

   z = a + 5

submodule B = submodule F {submodule  A }

This defines 3 submodules, 2 normal ones and a functor. At the moment we add implicit imports for simple modules, such as A, but not ones defined by instantiation (e.g., B).

I think it'd be more consistent to also add an import for B. We still can't add implicit imports for things inside B, because at this stage we don't know what F is, and therefore we can't tell what it defines (so we don't know what to import)