Log Volunteer Hours - assign added contacts to flexible need and save role to activity

Modify Log Hours post process to NOT create additional needs when a new contact is added. Instead we will retrieve the default flexible need for the project and link the activity to that need. Then we can save all the data in the 'new volunteer' row to the activity record (including role_id).

— original post —
Go to Log Volunteer Hours for an existing project and Add Volunteer. Fill in only the Contact Name + Actual Duration and Save. A new 'flexible' need is created with NULL visibility_id.

The presence of additional flexible needs messes up the Assign widget (each flex need becomes a new block on left side - see screenshot).

It also is undesirable for Needs UI (screenshot 2).

I think we should try and NOT create additional flex needs from Log Hrs, but need to evaluate.