[Auth] serve the full public key as base64 encoded string in the `info` endpoint

[jbygdell]

Please describe the feature As a user, I want the full public key in the info endpoint so that I don't have to do overly complex stuff to use it.

Acceptance criteria

• [ ] The public key bloc in the info endpoint serves the full key (when base64 decoded it should be plain text)
• [ ] Tests verifying the changes are added

Additional context The user should be able to do curl -sL HOSTNAME/info | jq -r '.public_key | @base64d' > pubkey.pem

Estimation of size: small

Estimation of priority: medium