Sprints/Iterations: Add Allocation % at iteration level for Product Owner, Team Coach, and Stakeholder

Issue Summary

There isn't a way to add/change the allocation for a Product Owner, Team Coach, or Stakeholder at the iteration level. Need to add the same functionality as we have for other roles such as Developer to these roles.

Today, if we add Product Owner, Team Coach, or Stakeholder at the Team Member level, you can set the allocations from 0-100%. However, if you add a person directly into the iteration, it sets the allocation to 0%. This may not be the correct percentage.

Steps to Reproduce

1. Step 1 - Navigate to team allocations
2. Step 2 - Update/Add Team Coach, Product Owner, Stakeholder to have allocations
3. Step 3 - Ensure those users are added to an iteration 
4. Step 4 - Compare allocation view on the iteration (should match)

Expected Results

Product Owner and Team Coaches should have an allocation % on sprints. 

Actual Results

Product Owner and Team Coaches does not have an allocation % on sprints. 

Workaround

No workaround for this issue at this time.