CCM-14566: Add FHIR validation to mesh-download

[simonlabarere]

Description

• Add new mappings for failure codes DL_CLIV_004 and DL_CLIV_005
• Update mesh.inbox.message.invalid event data to include an optional messageReference
• Update mesh-download lambda to pull schema dependency validation from https://github.com/NHSDigital/nhs-notify-digital-letters-onboarding
• Update mesh-download lambda to publish a mesh.inbox.message.invalid when the PDM FHIR resource is invalid

Context

We want to fail invalid FHIR resources early in order to notify trusts.

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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Sensitive Information Declaration

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• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.