Metrics basic auth

Description

Intent here was to provide a method for establishing a persistent metrics user for use with the serviceMonitor basic auth.

Previously the admin user was used for this process - this causes an issue due to the requirement (and recommendation) during initiation login to change the admin password (which subsequently breaks access to the metrics endpoint).

after a lot of back-and-forth for resulting implementation - it was decided that it was valuable to have a persistent user for metrics that is not the admin.

This implementation does require some nuanced upgrade documentation that is included in this Merge Request.

Issues

Relates to #49 (closed)