[PRMP-683] feat: Add SSH key expiry management for Transfer Family

[SanjayChopraNHS]

Overview

Jira ticket: PRMP-683

Description

We need to have some form of public key management in-place so that keys are rotated.

Context

As keys are created by the customer and supplied to us, rotation of keys is out of our control, but we can expire keys by removing them from the key store at a given age - 12 weeks being the standard, at which point we would email the customer to let them know that their key has expired and they need to provide a new key to continue using the service.

Checklist

Tasks for all changes:

• [x ] 1. I have linked this PR to its Jira ticket.
• 2. I have run git pre-commits. (WIP)
• 3. I have added and/or updated relevant tests.
• 4. I have updated relevant documentation.
• 5. I have considered the cross-team impact (and have PR approval from both Core & Demographics if necessary).
• 6. I have successfully deployed this change to a sandbox and witnessed unit and e2e tests passing:
  • 6a. Deploy - Sandbox - workflow run
  • 6b. SANDBOX Full- Deploy feature branch to sandbox - workflow run

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud