[module-imports] Improved Shadowing Behavior

[Gavin Bierman]

Dear experts,

We are used to single type imports shadowing a type imported from a package
import, i.e.

import java.awt.*;          
import java.util.List;      // Shadows the List from java.awt package

The design intent is that the more specific import can shadow the less specific
import.

With module imports there is a new case that I think we should support, where a
package import can shadow a module import, e.g.

import module java.desktop;
import java.util.*;

// List is resolved to java.util.List

This seems in spirit with the original design intent - the more specific import
can shadow the less specific import - we probably should have had this in the first
preview.

This also helps users who have used package imports up to this point be robust
against a future where a module import is added to their code.

I have updated the draft JEP to reflect this change:
https://openjdk.org/jeps/8335987

Please send any comments or suggestions to the list or to me directly.

Many thanks,
Gavin