Backend - Update validators

### Description
- Research when a call is needed and populate the ticket
- add validator for comparing our data to the NR data (fetch the latest NR data at file & pay)
* Validate NR data against schema
* Add validators for:
* Supported NR statuses only
* Non-expired NRs
* Supported request types only
* Supported Conditions/Consent statuses only
See story for specific validation requirements

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* If anything about the NR changes mid-draft, and the validation still passes, let them continue.
* If anything about the NR changes mid-draft, but the validation does NOT pass, frontend to show generic error and kick them out again **FOR MVP**
* Scott, Linda, Sienna to define better behavior for future ticket

### Requirements
See story for requirements doc

**Notes**
- no API ... here

The issue names no files or tests and refers to a separate story and requirements document; start there, then locate the backend entry point for NR validation and the latest-NR fetch. Confirm the schema, supported statuses, expiry, request types, and Conditions/Consent rules before estimating the work. Done criteria require populated requirements and agreed MVP behavior for invalid mid-draft changes.

Written by the indexing model from the issue text.