feat: DTOSS-10704 - Replace NEMS Subscriptions with new Caas based updates. Added ManageCaasSubscription function

[SamAinsworth-NHS]

Description

This branch introduces a new MESH-based CaaS subscription capability and shared MESH infrastructure, plus related infra/config updates and tests. The summary below reflects only changes unique to this branch compared with origin/main.

• New Azure Function app: ManageCaasSubscription
  • Endpoints: Subscribe, Unsubscribe (stub), CheckSubscriptionStatus, NemsSubscriptionDataService (pass-through), and a nightly PollMeshMailbox timer.
  • Sends a CAAS subscription request over MESH (Parquet payload with nhs_number) via a new shared sender. In dev, a stubbed sender can be used via IsStubbed.
  • Persists a record to NEMS_SUBSCRIPTION with SubscriptionSource = MESH.
• Shared MESH infrastructure under Shared/Common:
  • MeshMailboxExtension, MeshConfig/MailboxConfig to register the MESH client and mailboxes (supports Key Vault or local certs and server CA chain).
  • IMeshSendCaasSubscribe + MeshSendCaasSubscribe and MeshSendCaasSubscribeStub for local/dev.
  • IMeshPoller + MeshPoller for mailbox handshake validation.
  • CertificateHelper moved to Shared/Common/Utilities and reused by MESH-enabled functions.
• Database and model updates:
  • Migration adds nullable SUBSCRIPTION_SOURCE to dbo.NEMS_SUBSCRIPTION; new enum SubscriptionSource { NEMS = 1, MESH = 2 }; EF model updated.
  • ManageNemsSubscription updated to save new subscriptions with SubscriptionSource = NEMS.
• Function updates/alignment:
  • NemsSubscriptionService/NemsMeshRetrieval and CaasIntegration/RetrieveMeshFile updated to use the shared certificate parsing helper and cleaned imports.
• Transform service adjustments (no web changes):
  • Removed CurrentPosting lookup dependency from transform config/facade; updated transformRules.json to rely on PrimaryCareProvider/null checks and refined SMU/Welsh logic.
• Local/dev and infra configuration:
  • .env.example gains optional CAAS_SUBSCRIBE_TO_MAILBOX/CAAS_SUBSCRIBE_FROM_MAILBOX overrides for the new function.
  • compose.core.yaml adds a manage-caas-subscription service (disabled by default, with example env); compose.cohort-distribution.yaml removes CurrentPostingUrl.
  • Terraform env files add ManageCaasSubscription function app (stubbed by default) and remove obsolete CurrentPostingUrl wiring.
  • GitHub workflow stage-2-test.yaml ensures artifact upload runs with if: always() and ignores missing files. This means if a test fails the report is still uploaded to aid investigation.
• Tests:
  • Unit tests for MeshPoller, MeshSendCaasSubscribe, and ManageCaasSubscription.
  • Integration tests for the CAAS/MESH subscribe flow (Parquet assertions).
  • Playwright test data cleanup around older CAAS scenarios; test harness tweaks.

Context

This work progresses the move toward a MESH-based CaaS subscription path, standardising MESH client setup via shared infrastructure, adding a nightly mailbox handshake to validate connectivity, and recording subscription source for observability. It also removes a transform-time dependency on reference data (CurrentPosting) in favour of rule changes and primary-care-provider checks.

DTOSS-10704

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.

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
72.4% Coverage on New Code
2.6% Duplication on New Code

See analysis details on SonarQube Cloud