Steps to reproduce:

1. Under a buyer account, create a user via API
2. Go to the users list (/buyers/accounts/ACCOUNT_ID/users), and see in the State column that the new user has state "pending", but there is no button to activate the user.
3. Go to the user details by clicking on the Name, and see that again, there is no button/link to activate the user.

It seems to be because of this can?(:activate, user) condition here: https://github.com/3scale/porta/blob/a8cafe738d80ce3591fe9d349654bd68b2cfb930/app/helpers/buttons_helper.rb#L112C28-L112C49

I think this condition is not correct, as this ability is not set for the provider user, but they should be able to perform this action (as well as suspend/unsuspend).