Adding User Admins to Ping Request from UI

[vbhayden]

Morning team, adding a small update to provide the configured public admin keys to the ping API, so that the editor can behave properly when this is configured.

This is a sister PR for https://github.com/cassproject/cass-editor/pull/1363

Issue: Ping API does not currently include the public keys of users who are considered admins for the given CaSS instance.

Security Impact: Users configured as administrators through the environment variables will have admin controls within the CaSS Editor. Presumptive Impact: Admin functionality will be available to those users in the UI, in addition to simply the API commands which were granted in the previous PR for this.