feat: Add typed scale argument to derive macro

[Techassi]

Motivation

Customizing the scale subresource via #[kube(scale = r#"{}"#)] can feel very out-of-place and requires writing a raw JSON string. In addition, this can lead to a very long line, eg:

#[kube(
    version = "v1alpha1",
    kind = "MyScaler",
    namespaced,
    scale = r#"{"specReplicasPath": ".spec.replicas", "statusReplicaPath": ".status.replicas", "labelSelectorPath": ".spec.labelSelector"}"#
)]
struct ScalerSpec {}

Solution

This allows customizing the scale subresource by providing key-value items instead of a raw JSON string. For backwards-compatibility, it is still supported to provide a JSON string. However, all examples and tests were converted to the new format.

#[kube(
    version = "v1alpha1",
    kind = "MyScaler",
    namespaced,
    scale(
        specReplicasPath = ".spec.replicas",
        statusReplicaPath = ".status.replicas",
        labelSelectorPath = ".spec.labelSelector"
   )
)]
struct ScalerSpec {}