Refactor reCAPTCHA validator as form model

[aduth]

🎫 Ticket

Supports LG-12873

🛠 Summary of changes

Refactors reCAPTCHA validator classes to behave and validate as a form class.

See previous discussion: #10522 (comment)

📜 Testing Plan

Validate that there are no regressions in the expected behavior of reCAPTCHA phone validation.

Configure reCAPTCHA score threshold in config/application.yml

phone_recaptcha_score_threshold: 0.5

1. Go to http://localhost:3000
2. Create an account
3. When prompted to select MFA, choose phone
4. Enter an international phone number, e.g. +610491570006
5. In the reCAPTCHA score debugger tool, enter a value between 0.0 and 1.0
6. Click "Send code"
7. Observe that you are blocked if the score you entered was less than 0.5

[zachmargolis]

should we rename to Form and move to app/forms as well?

[aduth]

Yeah, I thought about that. We probably should, wasn't sure if the amount of noise it might add to this pull request might be worth doing it incrementally (i.e. separate pull request), especially since there's subclasses that might also need to be moved.

I did find that we have a couple other examples of form validators in services (e.g. SamlRequestValidator), though I think those probably ought to be moved as well.

[zachmargolis]

Some of the app/validator objects don't have the same interface as forms, but yes SamlRequestValidator seems to implement the Form interface

[aduth]

I will plan to move/rename this to app/forms, but will do that as a separate pull request, to keep diff noise to a minimum.

[zachmargolis]

does errors.merge! work with an entire validator? I'd expect more like

Suggested change

	recaptcha_validator.submit(recaptcha_token)
	errors.merge!(recaptcha_validator)
	recaptcha_validator.submit(recaptcha_token)
	errors.merge!(recaptcha_validator.errors)

[aduth]

That's what I initially expected as well, but it error'd because ActiveModel::Errors doesn't have an errors method; it's expecting the model, not the errors.