Configure ViperServ eggdrops to use Vault
Load Vault library and helper script.
Use Vault to connect to MySQL and to fetch nickserv password.
Provide a policy allowing to read apps/viperserv/
Provision AppRole credentials in .credentials file, and remove
MySQL information placeholder as it's known stored in Vault.
Test Plan: Launch eggdrop
Reviewed By: dereckson
Maniphest Tasks: T1733
Differential Revision: https://devcentral.nasqueron.org/D2687