Update to add logic to disable delete of people in Primary sections 

Summary of changes:
(1) Update the templates to disable delete icon for primary section
(2) Update unit testing
(3) Update urls.py to include sis_section_id as additional parameter to section_details
would it be more efficient to pass in the single boolean value `allow_delete` in terms of the sis_section_id check?  So, in the section_details view when you render the template you could pass in something like `allow_delete: sis_section_id == "None"`.  That way, you only need to change what the view renders and update this template, but you wouldn't have to touch either the _enrollments_list_by_name or _section_classlist templates.