R1:a1f08de28398

When viewing a workboard, only link to parent workboards in crumbs if parents have workboards

Summary:
Depends on D20516. See PHI1247. In D20331, I made the crumbs on workboards point at ancestor workboards.

However, this isn't a great destination if an ancestor doesn't actually have a workboard. In this case, point at the normal profile URI instead.

Test Plan:
- Viewed a milestone workboard with a parent that had no workboard. Saw a profile link instead of a workboard link (new behavior).
- Viewed…