Add support for server-side apply markers

[apelisse]

Follow-up from kubernetes-sigs/kubebuilder#1081

Kubernetes has a few new markers that could be really useful since they are also supported by CRDs. One can look at the existing kube-openapi implementation (since proper documentation is lacking ...)

• // +listType=[atomic|set|map]: Decides if the list is a set, an atomic map (fields are all replaced), or an associative list
• // +listMapKey=name: Indicates which field is the key for an associative list. Can only be used on lists that have the type "map". Can be repeated since multiple fields can be the key.
• // +mapType=[atomic|map]: decides if the map is replaced altogether when changed.

[DirectXMan12]

/kind feature
/priority important-soon