Site roles should add users to site permissions

[alexdryden]

In line with the goal of "zero side effect deactivation", users with roles that include site permissions should be added as site admins to sites in their teams.

This will also improve the admin experience when looking at the site users tab for a given site by avoiding the potentially confusing messaging currently present where a site may seem to have no users or fewer users than truly have roles with site permissions.

[alexdryden]

This would additionally help make core role assignment more flexible.

[alexdryden]

Bumping this as it will be required once Omeka S core implements a feature to only display relevant sites to users, so they will only see sites where they have a role. This filter will happen upstream from the Teams filter and so users of Teams would not be able to see their Team's sites unless they had a core role that gives them permission in all sites (which I think would not be affected by the new site list filtering feature) or if they were specifically added to the site with a permission