Iteration issue list doesn't include subgroup issues

The issues query on Iteration Report currently includes a group, which means we don't see issues for projects in subgroups

We need to either:

a) Add include_subgroups to issues b) Add Issues to global scope so we can have a top-level query for issues and not include groupPath at all

---

When doing a query like:

group(fullPath: $groupPath) {
  issues {
    ...
  }
}

We do not include the issues from project in subgroups. IssuesFinder already supports this with the include_subgroups option.

We could consider always including subgroups or adding an extra argument so we can specify if we also want issues under subgroups.

This is used in our Iterations report page so it is causing a ~bug there