Add open_access field to Resource model for access control

atlas/models.py

@@ -1893,6 +1893,11 @@ class Resource(models.Model, AuthorMixin):
         help_text='Subspecialty or subspecialties this resource relates to.',
     )
 
+    open_access = models.BooleanField(
+        default=True, 
+        help_text="If true the resource is available to all users, otherwise only in the context of cases."
+    )
+
     def __str__(self) -> str:
         return self.name