Shifting to tag-based functionality for registration questions & attendance/check-in

[danielamassiceti]

Included in this PR:

• A change in the way answers to registration questions are extracted and attached to an AttendanceUser. Previously a user's answers were extracted by searching for specific question strings (e.g. 'Are you bringing a poster?'). This PR instead adds functionality for answers to be extracted by a tag attached to a question. Specifically, for a given user, all the registration questions that have been tagged by an admin (functionality to do this is not included in this PR, though a new tag_type = QUESTION has been added) are pulled from the dataset, and then their corresponding answers are extracted.
• Added a new RegistrationQuestionTag model
• Removed accommodation award, tshirt and poster fields from attendance, in place of a registration_metadata and offer_metadata fields which are lists of dicts containing relevant info. registration_metadaset contains name/response pairs for all the registration questions which had tags and the user's corresponding answers. offer_metadata just extracts the names of the tags attaches to the user's offer.
• The front-end check-in functionality then simply loops through the registration_metadata, and displays it. Currently, the offer_metadata is not shown though can easily be added.
• Shifted some tag stringify functionality to the TagAPI class (from the OfferAPI class), so it can be used more broadly
• Some small bug and comment fixes

I have tested this very briefly. Will continue testing over the next days.

[avishkar58]

This looks great! Always a pleasure to read your code! :))
Will wait until you've added the tests to approve.

[danielamassiceti]

Completed some more systematic testing and all looks good. Adding the scenarios I tested here for our records:
--industry prof with accepted offer, registered, not paid, not signed online indemnity form -- can't be checked in due to no payment
--industry prof with accepted offer, registered, not paid, signed online indemnity form -- can't be checked in due to no payment
--industry prof with accepted offer, registered, paid, not signed online indemnity form -- PASSED
--industry prof with accepted offer, registered, paid, signed online indemnity form -- PASSED
--phd with accepted offer, not registered, not paid, not signed online indemnity form -- PASSED; can be checked in (even if they haven't paid) since they haven't registered
--phd with accepted offer, not registered, not paid, signed online indemnity form -- PASSED; can be checked in (even if they haven't paid) since they haven't registered

--invited guest, not registered, not paid, not signed online indemnity form -- PASSED; payment not required for invited guests
--invited guest, not registered, not paid, signed online indemnity form -- PASSED; payment not required for invited guests
--invited guest, registered, not paid, not signed online indemnity form -- PASSED; payment not required for invited guests
--invited guest, registered, not paid, signed online indemnity form -- PASSED; payment not required for invited guests

--invited guest with offer, not registered, not paid, not signed online indemnity form -- PASSED, payment not required for invited guests
--invited guest with offer, not registered, not paid, signed online indemnity form -- PASSED, payment not required for invited guests
--invited guest with offer, attendeee-registered, not paid, not signed online indemnity form -- PASSED, payment not required for invited guests
--invited guest with offer, attendee-registered, not paid, signed online indemnity form -- PASSED, payment not required for invited guests
--inivted guest with offer, guest-registered, not paid, not signed online indemnity form -- PASSED
--inivted guest with offer, guest-registered, not paid, signed online indemnity form -- PASSED

[danielamassiceti]

Noting that we only check the 'confirmed' field in a user's registration entry to determine if they have paid or not. If they have not registered and not paid, then they can still be checked in.

We've left this as-is for Indaba 2023, as all attendees have registered, but I have logged a bug here for future events.