Make response expiry date mandatory for both launch formats

[petechd]

What is the context of this PR?

This updates both v1 and v2 RM to eQ Runner payload formats and updates response_expires_at property. response_expires_at is required to be a mandatory field sent from RM now and is always validated/doesn't default in eq Runner at launch hence this change.

Links

Check the change is correct and that the updated example schemas pass validation.

Checklist

• Changes to the spec have been added to example schemas in examples/
• JSON Schema definitions have been updated

[petechd]

Make response expiry date mandatory for eQ Runner (1 SP)

[MebinAbraham]

Need to update launch_v1.json and launch_v2.json to mark response_expires_at as mandatory. Other than that, LGTM.

[pricem14pc]

For completeness, confirming that response_expires_at is populated with the value of the mandatory event date exercise_end. Collection exercises cannot go live without the business adding this.