allow team leaders to edit their teams

[marcoieni]

We want to give team leaders permission to approve PRs in this repository, so that they can unblock their teams.

The question is: how much permission can we give them? If you look at the CODEOWNERS file, you can see that anyone with write access can approve PRs in the /people /repos and /teams directories.
But what if an attacker compromises a team-lead's account? They could then approve their own PRs
to remove branch protection rules, kick out team members, or archive all rust-lang repositories.

To prevent this, we want to limit the permissions of team-leads to only the directories they own,
i.e. their /teams and the /repos owned by their teams.

With this PR, I start by giving team-leads write access to their own /teams directory.

Con of this approach: team-repo-admins and mods will be notified about every change in the people, teams and repos directory.

• If this is approved, merge the leads = "write" before this PR, so that team leads have write access

[marcoieni]

unfortunately with this approach we need to add specific owners in these generic directories, otherwise the team-leads will have the same permissions of team-repo-admins and mods, i.e. they could approve PRs on all these toml files

[github-actions]

Dry-run check results

[WARN  sync_team] sync-team is running in dry mode, no changes will be applied.
[INFO  sync_team] synchronizing github
[INFO  sync_team] 💻 Repo Diffs:
    📝 Editing repo 'rust-lang/team':
      Permission Changes:
        Giving team 'leads' write permission