Create CODEOWNERS file for all repositories and assign team

[kenoir]

In order to properly assign responsibility for merging changes and resolving vulnerabilities, and also notify the appropriate team about PRs that should be merged we should assign a CODEOWNERS containing either the @wellcomecollection/digital-platform or @wellcomecollection/digital-experience teams.

https://docs.google.com/spreadsheets/d/1swcpgKb2mN0JcpG5msvxgLT52VC1H1CoTrESXnys5p0/edit?usp=sharing

Those teams should be assigned "admin" rights on those repositories.

Follows an action from retrospective: https://www.notion.so/wellcometrust/Digital-Platform-sprint-plan-16-30-October-2024-1146687658a1808b9872d125d883b45a