Fix #398: Include inherited members in the PackageRef fallback lookup.

If we have a `package object` that extends other classes, we may
have to look member selections among inherited members. This is
done by `getMember` instead of `getDecl`.

To test this, we need a Scala 2 `package object` with an `extends`
clause. There is no such thing in the standard library, which is
our only source of Scala 2 code, unfortunately. So we don't add a
test for that.

tasty-query/shared/src/main/scala/tastyquery/Types.scala

@@ -1190,7 +1190,7 @@ object Types {
             .allPackageObjectDecls()
             .iterator
             .map { cls =>
-              cls.getDecl(name) match
+              cls.getMember(name) match
                 case None       => ResolveMemberResult.NotFound
                 case Some(decl) => makeResult(decl, cls.moduleValue.get.staticRef)
             }