[Issue] Ensure that invoice comments are returned when requested by GraphQL queries

[m2-assistant]

This issue is automatically created based on existing pull request: #31606: Ensure that invoice comments are returned when requested by GraphQL queries

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Description (*)

As part of the GraphQL schema for customer orders, invoices can be requested, along with their comments. However, the current implementation does not return any comments for invoices, resulting in a null value always.
This pull request ensures that invoice comments (that are visible in the front-end) are returned when requested in the query.

Fixed Issues (if relevant)

1. Fixes magento/magento2#<issue_number>

Manual testing scenarios (*)

1. Create a customer order and an associated invoice.
2. Add a number of comments to an order invoice, including both visible and not visible in the front-end.
3. Call the customer GraphQL query, requesting orders, invoices and their associated comments - e.g:

query {
    customer {
        orders(filter: { number: { eq: "000000154" } }) {
            items {
                invoices {
                    comments {
                        message
                        timestamp
                    }
                    items {
                        product_name
                    }
                }
            }
        }
    }
}

Questions or comments

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds are green)

Resolved issues:

1. resolves [Issue] Ensure that invoice comments are returned when requested by GraphQL queries #31643: Ensure that invoice comments are returned when requested by GraphQL queries

[aligent-lturner]

This is a duplicate of #31643