matomo roles are not useful out of the box

[diosmosis]

Currently, WordPress users can be assigned special Matomo roles: Matomo Admin, Matomo Write, Matomo View, Matomo Super User, but doing so results in a user that can't view the WordPress admin.

Ideally, users would be able to assign multiple roles to a user, and while WordPress supports this, it provides no UI to actually do it. Simply telling plugin users to create WP users with a Matomo role could thus easily result in confusion for users that are not WordPress experts.

Instead, we should either:

• allow adding Matomo specific capabilities to existing users
• recommend using another plugin to be able to add multiple roles to a user