Add CODEOWNERS File to Template Repo and The Project Template

[sanjeevz3009]

What is the context of this PR?

• Added a CODEOWNERS file to the template repo itself.
• Added a functionality where an automatically CODEOWNERS file is created for a generated template repo.
  • Additionally, the developers are able to specify their code owner, and it will be reflected in the generated CODEOWNERS file.

How to review

• Test the changes locally:
  • By default, the generated template repo should contain a CODEOWNERS file.
  • When entering your own code owner config, it should be reflected in the generated template repo.

Follow-up Actions

List any follow-up actions (if applicable), like needed documentation updates or additional testing.

[sanjeevz3009]

@MebinAbraham, I will be addressing the security issues first to unblock this PR:

Issue on this PR: https://github.com/ONSdigital/ons-python-template/actions/runs/21320427041/job/61369465520?pr=124

Security issues:

• Bump copier from 9.11.1 to 9.11.2 in the py-security-updates group across 1 directory #123
• Bump the py-version-updates group across 1 directory with 3 updates #122