Remove usage of maps

[johscheuer]

Like stated in this comment: https://github.com/FoundationDB/fdb-kubernetes-operator/pull/380#discussion_r525134130 we should remove maps where possible n the API.

[brownleej]

I went through the CRD YAML files looking for occurrences of "additionalProperties", which seems to signal the use of a map type in the CRD. Most of the cases I found were either deprecated or coming from core Kubernetes types like the pod spec. Here are the cases I found that are active and coming from our types:

• cluster.spec.processes
• cluster.spec.sidecarVersions

Both of these could potentially be converted to lists of named sub-objects.

[johscheuer]

The sidecarVersions is already deprecated and only cluster.spec.processes is left. I think the best way to represent this and being conformant with the Kubernetes API guidelines is something like this:

type FoundationDBClusterSpec struct {
    ...
    ProcessesConfigs []ProcessesConfig
    ...
}

type ProcessesConfig struct {
    Class ProcessClass
    settings ProcessSettings
}

I can try to squeeze that into my list of work items this week.

[johscheuer]

The change to the ProcessConfigs might be a good choice for the conversion: https://github.com/FoundationDB/fdb-kubernetes-operator/issues/1047