Avoids N+1 query issues when loading many epics including their epics.
Batch loader is used for loading these items, downside is that we
load all issues for each epic into memory - given the use-case this
should be acceptable (number of issues per epic is relatively small).
To avoid extra queries/checks, we authorize only issues being rendered
instead of the whole array - downside is that less-than-limit number of
items may be returned then.