The upgrade package duplicaes some of code due to relative
imports between entry-points. This caused bundlers to
inline shared functions twice in both FESM outputs.
This is an acceptable limitation and we are not changing this
because the primary entry-point is not synced into G3. It's non-trivial
to remove these cross relative imports right now because the primary
entry-point is not even built in G3 so instead we just ignore the
relative imports using a re-export file.
Note: To simplify this change, we continue using namespace exports
as exporting individual named exports for all these possible usages
is rather cumbersome and also we had existing namespace imports for
e.g. `angular1.ts`. The code of upgrade is rarely edited these days
PR Close#51500
