feat: add an admin endpoint for the Digital Planning Application format

[jessicamcinchak]

Connecting all the dots finally from schemas definitions ➡️ planx-core passport mapping ➡️ this admin endpoint !

Testing:

• It loads a valid Planning Permission session: https://api.2322.planx.pizza/admin/session/81bcaa0f-baf5-4573-ba0a-ea868c573faf/digital-planning-application
• It logs errors for an incomplete/invalid session: https://api.2322.planx.pizza/admin/session/d087a422-2ae7-42fc-906f-225d00c9a957/digital-planning-application (this is a bit tricky because planx-core mapping errors will bubble up before actual schema validation errors - but we want to prioritise the latter? can be addressed in a followup PR!)

Next steps:

• The new schema borrows from BOPS, which means it might be subject to some of the same timeout errors we've been seeing this past week - let's keep testing this (it'll just be in admin endpoint form, so lower stakes)
• Once merged to production/staging, let's ensure all recently submitted LDC apps validate successfully! If they don't, what have we missed → fix schema or passport mapping?
• Properly add example responses to Swagger (needs to happen across formats!)

[github-actions]

Removed vultr server and associated DNS entries

[DafyddLlyr]

Brill! Endpoints work as expected 👌

Properly add example responses to Swagger (needs to happen across formats!)

Yeah I've been wondering about this also! Technically this endpoint's Swagger doc will be a translation of the 18,000 line Digital Planning Schema 👀

Using $ref we could point to an external Swagger doc - https://swagger.io/docs/specification/using-ref/

Maybe we also build and publish a Swagger spec from the JSON schema using something like https://www.npmjs.com/package/@openapi-contrib/json-schema-to-openapi-schema

Or maybe we don't describe our return type explicitly and in the docs write a description which just links to the repo / schema?