Done

Add actions for PS7 Demos.
Add terraform files for the PS7 Demos configuration.

How to QA

• Check that there's a comment with a link to PS7 Demo.
• Check that the new actions ran successfuly.
• Go to the PS7 Demo and check that the website runs well.

Testing

• This PR has tests
• No testing required (explain why): Just added GH Actions and Terraform config files.

Security

• Security considerations for review (list them):
  • Examples:
  • Access control: users can only access their own data
  • Input: user input is validated and sanitised
  • Sensitive data: secret or private data is not exposed in any way
• This PR has no security considerations (explain why): Just CI/CD code to deploy on PS7 Demos.

UX Approval

• This PR does not require UX approval
• This PR does require UX approval (add context): CI/CD improvements