Make Traefik's basic authentication configurable

[ricsanfre]

Issue Description

Traefik basic authentication user/password is hardcoded. This basic authentication mechanism is used for those HTTP services lacking of its own authentication process (longhorn, traefik, prometheus, etc.).

Traefik ansible role should be modified to make user/password configurable.

Implementation details

• Use of htpasswd tool for generating automatically the user/password taking as inputs role variables