[MR Widget] Add Engineering DRIs as CODEOWNERs
<!-- This template is a great use for issues that are feature::additions or technical tasks for larger issues.--> ### Proposal In the context of the ~"WorkingGroup::MergeRequestReportWidgets", we have devised a [list of DRIs for the engineering of each widgets](https://about.gitlab.com/handbook/engineering/development/dev/create/code-review/report-widgets-dri-list.html). With the Working Group approaching it's extinction, it's important to start thinking about life after the working group. In a recent discussion, it came up the idea of adding each DRI as CODEOWNER for each of their widgets. That would crystalize their ownership in code rather than simply in documentation. <!-- Label reminders Use the following resources to find the appropriate labels: - https://gitlab.com/gitlab-org/gitlab/-/labels - https://about.gitlab.com/handbook/product/categories/features/ -->
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