Add Image specification to different components

[lbroudoux]

Reason/Context

While working on #41, I realized we hadn't introduced image specification capability for components yet. Having the ability to specify images coordinates for each component is foundational.

Description

We should align on latest Helm chart improvements that allows specifying images using this kind of block:

keycloak:
  image:
    registry: quay.io
    repository: keycloak/keycloak
    tag: 24.0.4
    digest: 

If sha 256 digest is provided, it takes precedence on tag specification to allow pinning images.

Implementation ideas

No response