Validate attestation against config

[kriswest]

Describe the bug

The API currently validates attestations submitted against the definition of the attestation form submitted with the request:

git-proxy/src/service/routes/push.js

Line 89 in 4387684

const attestationComplete = questions?.every((question) => !!question.checked);

To ensure attestations are completed correctly, they should be validated against the requirements set in the configuration, rather than the copy submitted with the request.

Expected behaviour
If a request is submitted with an incomplete attestation (i.e. with an element missing, rather than just an element that's not checked).