Update codeowners configuration

[marlass]

In order for us to have more control and better reviews, we need to protect some areas of Spartacus to make sure that the proper people reviews any changes done to them

• [ ] Come up with a draft of owners for all of the codebase owned by the Core team
• [ ] Decide between Github teams vs individual owners
• [ ] Make sure codeowners can handle multiple owners
• [ ] If yes, Bring back codeowners. If not, find another solution

[Platonn]

1. I suggest creating a Github team for the Spartacus core team. @hackergil do you think you could create it?
2. And then we could assign the Github Spartacus core team as codeowners of our libs and shared code.

That said, Github teams are sometimes cumbersome to manage - to have a permission to add/remove from a team, you need to be in that team.

In the future if we're assigning specific people as owners of certain fine-grained features, we might not want to rely on the Github sub-teams. Instead, we could use the direct github nicknames @ to avoid problems with teams management.

Reference: list of existing github teams https://github.com/orgs/SAP/teams/spartacus-project-team/teams