Implement code owners

What does this MR do?

Implement code owners

Implements code owners feature by adding .gitlab/CODEOWNERS.

References:

• https://docs.gitlab.com/ee/user/project/codeowners
• https://docs.gitlab.com/ee/user/project/codeowners/reference.html
• Add codeowners file for the CNG project (gitlab-org/build/CNG!1488 - merged)
• Add the codeowners file that allows us to restr... (gitlab-org/charts/gitlab!3313 - merged)

Testing

Confirm no syntax errors in https://gitlab.com/gitlab-org/cloud-native/gitlab-operator/-/blob/add-codeowners/.gitlab/CODEOWNERS.

There will be some 'zero owner' warnings. See gitlab-org/charts/gitlab!3313 (comment 1509846683).

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.

Related issues

Related to https://gitlab.com/gitlab-org/distribution/team-tasks/-/issues/1348#note_1523980784

Related to gitlab-org/distribution/team-tasks#1253 (closed)