Publish Vault certificate information

Summary:
Vault PKI exposes several end-points to get certificate information.

Those doesn't require authentication and are safe to use and expose.

Fixes T1743.

Test Plan: Browse URLs

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1743

Differential Revision: https://devcentral.nasqueron.org/D2812