Declarative GitHub Membership Administration

[timuthy]

What would you like to be added:
Adding individuals to different GitHub teams should be done automatically, based on a declarative approach.
The implementation can follow the approach used by Kubernetes, which utilizes the https://github.com/kubernetes/org repository along with Prow/Peribolos (see gardener/documentation#715 (comment)).

Action Items:

• Extract and check-in Gardener org data Define Gardener Org via peribolos #31
• Activate Peribolos Apply Gardener Org config via peribolos ci-infra#6532
• Update Community Roles documentation#1016
• Add Gardener repositories to org.yaml #80
• Activate maintenance of repositories with peribolos ci-infra#6917

Why is this needed:

• Traceable memberships
• Owner separation per GitHub team(s)
• Less manual work

[gardener-ci-robot]

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This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 60d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 60d of inactivity since lifecycle/rotten was applied, the issue is closed

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/lifecycle stale

[timuthy]

/remove-lifecycle stale

[timuthy]

/assign @oliver-goetz