Add feature for supplementalGroups

[jonra82]

Preflight Checklist

• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for an issue that matches the one I want to file, without success.

Problem Description

Some enterprises have strict policies on pod and container level. For example I have a case where Dex is used in an organization where at the same they use Kyverno and enforce a policy to use supplementalGroups between ranges 100-200 and 500-600. Dex chart as of writing has no support for it.

Proposed Solution

Add supplementalGroups list\array to values.yaml under podSecurityContext values.

podSecurityContext: {}
##fsGroup: 2000
##supplementalGroups: [] <--

Alternatives Considered

No response

Additional Information

No response