Add link next to org team members allowing them to be removed

This adds a link next to the organisation team members which lets
them be removed from the organisation. Service team members have
their own page and the link to remove them appears there. For
organisation team members, we don't currently have any other
information we want to show or any  other actions to perform. As
a result, this change uses the 'Team members' page to show the
confirmation banner.

The endpoint called 'edit_user_org_permissions' was renamed to
'edit_organisation_user' and some of the existing code around deleting
org users (which didn't work) was changed.

app/navigation.py

@@ -341,7 +341,7 @@ class OrgNavigation(Navigation):
 
         },
         'team-members': {
-            'edit_user_org_permissions',
+            'edit_organisation_user',
             'invite_org_user',
             'manage_org_users',
             'remove_user_from_organisation',