New permission: Settings (eHoldings): Can assign/unassign a user from a KB

As a system administrator
I only want select staff to assign/unassign user(s) to a KB
To prevent any assignment conflicts

Requirement

• Create the requirement - [Settings (eHoldings): Can assign/unassign a user from a KB]
• A user with this permission
  • Sees the Assigned Users page
  • Able to assign/unassign a user to/from a set of KB credentials

• A user without this permission
  • Does not see the Assigned Users page
  • AND cannot assign/unassign a user to/from a set of KB credentials