feat: add option to use "Pay without pay" and show error in cases of undefined fee

[jessicamcinchak]

Changes:

• Adds Editor option to "Hide the pay buttons and show fee for information only" (off by default)
  • Renders like this in the public interface
• Updates how NaN / undefined fees are handled
  • Current behavior: if the data field referenced by the Pay component (props.fn) is undefined when Pay is reached, then automatically skip the Pay component. This led to real applications being successfully submitted without paying because of a content error a few weeks ago.
  • New behavior: if props.fn is undefined when Pay is reached, display an error and do not let the applicant continue. An airbrake error including the sessionId is also thrown/should be picked up in Slack.

Testing:

• Try the different paths in this flow and confirm you have expected behavior: https://2284.planx.pizza/lambeth/pay-without-pay-test/preview
• Confirm that teams that do not have GOV.UK Pay enabled still show the expected error: https://2284.planx.pizza/barking-and-dagenham/pay-test/preview (specifically with a "Continue" button that does not prevent you from proceeding with your test)

Future scope / not addressed here:

• The Pay component is still automatically skipped in cases where the fee = 0. My understanding is we don't want to "show" this case until we can properly design how to display "reasons" (eg resubmission or exemption or other calculation)
• Show a breakdown of how the fee was calculated (currently on roadmap here 🔮)

[jessicamcinchak]

Display rather than hide undefined or zero Pay components (Pay without pay)

[jessicamcinchak]

Allow Pay component to display fee for information only without payment option

[github-actions]

Removed vultr server and associated DNS entries

[jessicamcinchak]

This accessibility test at the top-level of Pay was actually meaningless (it was testing the "skipped scenario" 👻), so now there's 3 accessibility tests running against the Confirm child component container in its various states:

[DafyddLlyr]

Looking great! All behaviour working as expected - thanks for also adding more a11y tests which is always good to see.

A few small comments on the code, but no show stoppers.