feat: code based attendance toggle

[ElijahFeldman7]

django admin users have this tab where they can set a and b block codes, export csv, edit and delete attendance for previous days or the current day

csv export is sorted by last name for easy attendance marking

people can type in the code. if it is right, they are added to a csv

for testing, toggle in validation_settings.json the

"enable_code_attendance": false -> true

this is for if sponsors are comfortable with this in the future.