AFE dummy API calls and form validation

[bencodeorg]

This PR:

1. Adds a route to allow us to actually submit data to AFE. It seems like it should be relatively straightforward to submit to Pardot, but our tests of the route aren't working (we've reached out to AFE for guidance). I've included a dummy URL for now.
2. Does validation on the form -- namely, it a) does not allow users to move from the first step (email and school) to the second step until they've filled out both fields, and b) does appropriate requiring of fields in the second step. Eg, it requires shipping address fields if you've said you want the "inspiration kit".

To dos:

1. Actually make API work (waiting on response from AFE).
2. Second API call to CSTA JotForm API endpoint.
3. The school validation doesn't work as I'd like currently -- it won't let you progress without choosing a school, but doesn't appropriately circle the school dropdown in red if it's empty.
4. Dedupe a lot of the repetitive code that creates checkboxes / text fields.
5. Use submitted variable to keep track of whether we've submitted this users data before.

Testing story

Manual testing still for client side validation. Added some basic initial tests for the new controller action.

Reviewer Checklist:

• Tests provide adequate coverage
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[islemaster]

👍 Excellent incremental step

[islemaster]

Just a reminder that we'll want to actually require an authenticity token before we're done with this feature.