[LUPEYALPHA-1109] Validation for missing practitioner email

[vacabor]

Adds a validation when trying to submit a claim without supplying a practitioner email address.

Marking as draft because I don't like this approach:

• I think there is an underlying bug: It seems selecting "permanent" making the claim ineligible, and then going back to change the contract type, sends the user to the "check your answers" page without asking them for the practitioner email address - I'm still looking into this
• This error doesn't link to anywhere and we don't have a design pattern for errors within a summary list

[github-actions]

Deployments

Journey	URL
Additional Payments	https://claim-additional-payments-for-teaching-review-3247-web.test.teacherservices.cloud/additional-payments/claim
Student Loans	https://claim-additional-payments-for-teaching-review-3247-web.test.teacherservices.cloud/student-loans/claim
Further Education	https://claim-additional-payments-for-teaching-review-3247-web.test.teacherservices.cloud/further-education-payments/landing-page
Early Years Payment	https://claim-additional-payments-for-teaching-review-3247-web.test.teacherservices.cloud/early-years-payment/landing-page
Relocation Payments	https://claim-additional-payments-for-teaching-review-3247-web.test.teacherservices.cloud/get-a-teacher-relocation-payment/landing-page
Admin	https://claim-additional-payments-for-teaching-review-3247-web.test.teacherservices.cloud/admin

[vacabor]

Closed in favour of #3253.