Backport of Introduce high privilege namespace (administrative namespace) into release/1.13.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #21215 to be assessed for backporting due to the inclusion of the label backport/1.13.x.

🚨

Warning automatic cherry-pick of commits failed. If the first commit failed,
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The person who merged in the original PR is:
@biazmoreira
This person should manually cherry-pick the original PR into a new backport PR,
and close this one when the manual backport PR is merged in.

merge conflict error: POST https://api.github.com/repos/hashicorp/vault/merges: 409 Merge conflict []

The below text is copied from the body of the original PR.

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Full functionality only works in enterprise. This adds the core implementation pieces needed.

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Overview of commits

• 4c1a7b5

[hashicorp-cla]

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1 out of 2 committers have signed the CLA.

• biazmoreira
• temp

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[tomcf-hcp]

Closing this pull request. Completed with this pull request: #21647