Add relationship button is visible to project users

[seav]

Steps to reproduce the error

1. Log-in as a project user.
2. Go to the "Relationships" tab of an existing location.

Actual behavior

• If there are existing relationships, there is a + Add button on top of the table of relationships.
• If there are no existing relationships, there is a + Add relationship button and the message “To add your first relationship, select the button below.”

Expected behavior

The opposite of the above (no buttons and message) because project users have no write access to the project.