Introduce a role filter for users in admin dashboard

[gtsiolis]

Problem to solve

Querying all instance users with admin privileges has been brought up a couple of times.

Currently, searching for users in /admin is not able to filter only for user admins.

See relevant discussions[1][2] (internal).

Proposal

Introduce a way to filter users with admin privileges from the admin dashboard.

Designs

TBD (To be discussed)

See also draft design proposal from relevant discussion (internal).

... here’s a draft design for #10976 towards moving the tabs and potentially introducing a second row of tabs in the /admin area.

Tabs in /admin

[stale]

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