Shopper: Authorization bypass and RBAC privilege escalation in team settings

Shopper is a Headless e-commerce Admin Panel. Prior to 2.8.0, two distinct authorization defects in the team settings allowed any authenticated panel user to take over the RBAC system. Settings/Team/Index had no mount() authorization. Any authenticated user could load the page and use its public actions to create new roles and delete other users, including administrators. Settings/Team/RolePermission gated its write actions on the read-only view_users permission. Any user holding view_users could grant themselves or any other user arbitrary permissions, including manage_users and edit_orders, effectively escalating to full panel administrator from a read-only account. Combined, these two defects allow a low-privilege authenticated user to obtain administrator privileges and remove the legitimate administrators from the panel. This vulnerability is fixed in 2.8.0.