Allow traits to be configured via configmap/secrets

[agiertli]

Right now the trait configuration values are hardcoded in the Integration or KLB itself.

It would be useful to have a possibility to externalize that configuration. Example CLI command could look like:
-t container.cpu={{configmap:mycm/cpu}}

This is especially important in context of "kamel promote" feature, because if you can't externalise config, then you are forced to re-use the same trait configuration values across environment. Good example is container trait - where you typically have different values for mem/cpu/replicas across dev and prod.

[squakez]

It could be that one, or maybe also any properties available in application.properties, being the properties also configurable from a Configmap or a Secret.

[squakez]

With the presence of the dry-run provided in #4050 it should makes sense to post process any profile with Kustomization style approach. Ideally with the new feature, you will kamel promote ... -o yaml that would produce an Integration CR on top of which we can apply any customization via kubectl apply -k. I am closing this in favour of the aforementioned approach.