When listing ACLs on an endpoint, the "Shared With" column doesn't output anything for principal_types all_authenticated_users and anonymous
The final line of the interpretation function returns `principal` for non-group/identity principals, but `principal` isn't going to be set for special `principal_type`s.

diff --git a/globus_cli/commands/endpoint/permission/list.py b/globus_cli/commands/endpoint/permission/list.py
index 7c53d68..9e4253b 100644
--- a/globus_cli/commands/endpoint/permission/list.py
+++ b/globus_cli/commands/endpoint/permission/list.py
@@ -28,6 +28,8 @@ def list_command(endpoint_id):
             elif rule['principal_type'] == 'group':
                 return ('https://www.globus.org/app/groups/{}'
                         ).format(principal)
+            else:
+                principal = rule['principal_type']
             return principal
 
         print_table(rules, [('Rule ID', 'id'), ('Permissions', 'permissions'),
['globus_cli/commands/endpoint/permission/list.py']