i18n - set CODEOWNERS for specific languages

[bbovenzi]

Body

Let's add CODEOWNERS for specific languages to ensure an active Airflow contributor can maintain translations.
We should make sure there are CODEOWNERS who can maintain a language before we accept a new one.

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.

[Lee-W]

I can help with Mandarin

[DjVinnii]

I could help with Dutch if needed

[choo121600]

I can help with Korean 🙌

[bugraoz93]

I can help with Turkish if there is intent to release it :)

[potiuk]

Polish from my side.

[shahar1]

Now that we have the i18n policy implemented and the CODEOWNERS file - maybe we could close this issue?
We could create an issue to track the creation of new languages.