CCM-8270: Aggregate error items

[simonlabarere]

Summary

This is a minor change to accommodate this BE PR: https://github.com/NHSDigital/comms-mgr/pull/515 in order to:

• Use the status code returned by the BE for each error item
• Not populate the source on an error item when it's not provided by the BE
• Allow the BE to return 404 errors and translate them instead of just returning a generic error

Note that the internal-dev tests can only pass with the new BE.

Reviews Required

• Dev
• Test
• Tech Author
• Product Owner

Checklist

• Brief description of work completed, and any technical decisions made as part of the PR
• PR link added as a comment to the relevant JIRA ticket
• PR link shared on Slack and/or Teams
• 2 reviews received
• Tester approval

[github-actions]

This branch is work on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

CCM-8270

[github-actions]

This branch is work on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

CCM-8270

[github-actions]

This branch is work on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

CCM-8270

[github-actions]

This branch is work on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

CCM-8270

[github-actions]

This branch is work on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

CCM-8270

[github-actions]

This branch is work on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

CCM-8270

[github-actions]

This branch is work on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

CCM-8270

[github-actions]

This branch is work on a ticket in the NHS Digital APM JIRA Project. Here's a handy link to the ticket:

CCM-8270