Add support for component host configuration through values in Helm chart.

[Faylixe]

The Helm chart design actually partially support usage of external component, especially for storage. Indeed, support for Postgres, Redis, and Vespa dependencies allow enabled flag to prevent from deploying such solutions, but external host configuration is not permitted as it is injected into the chart configmap without any possibilities of tuning.

One could say you can always override it by envvars but since they already are statically defined here, it seems unnatural :). Just adding the possibility to define those variable through values would be more explicit.