2047: Add LabelsFromPath functionality to Info metrics

[murphd40]

What this PR does / why we need it:

This PR adds LabelsFromPath functionality to Info type metrics defined via a customresourcestate.Resource

How does this change affect the cardinality of KSM: (increases, decreases or does not change cardinality)

May increase under certain conditions (use of custom resource metrics of type info)

Which issue(s) this PR fixes

Fixes #2047

---

Testing

• unit tests updated ✅
• manually verified:

package main

import (
	"fmt"
	"strings"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/kube-state-metrics/v2/pkg/customresourcestate"
)

func main() {

	foo := unstructured.Unstructured{
		Object: map[string]any{
			"status": map[string]any {
				"sub": map[string]any {
					"type-a": map[string]any {
						"active": 1,
						"ready": 2,
					},
					"type-b": map[string]any {
						"active": 3,
						"ready": 4,
					},
				},
			},
		},
	}

	r := customresourcestate.Resource{
		GroupVersionKind: customresourcestate.GroupVersionKind{
			Group: "myteam.io",
			Version: "v1",
			Kind: "Foo",
		},
		Metrics: []customresourcestate.Generator{
			{
				Name: "gauge",
				Each: customresourcestate.Metric{
					Type: customresourcestate.MetricTypeGauge,
					Gauge: &customresourcestate.MetricGauge{
						MetricMeta: customresourcestate.MetricMeta{
							Path: []string{"status", "sub"},
							LabelsFromPath: map[string][]string{
								"active": {"active"},
							},
						},
						LabelFromKey: "type",
						ValueFrom: []string{"ready"},
					},
				},
			},
			{
				Name: "info",
				Each: customresourcestate.Metric{
					Type: customresourcestate.MetricTypeInfo,
					Info: &customresourcestate.MetricInfo{
						MetricMeta: customresourcestate.MetricMeta{
							Path: []string{"status", "sub"},
							LabelsFromPath: map[string][]string{
								"active": {"active"},
							},
						},
						LabelFromKey: "type",
					},
				},
			},
		},
	}

	f, _ := customresourcestate.NewCustomResourceMetrics(r)
	
	fgs := f.MetricFamilyGenerators(nil, nil)

	sb := strings.Builder{}
	for _, fg := range fgs {
		mf := fg.Generate(&foo)
		sb.WriteString(mf.Name + "\n")
		for _, m := range mf.Metrics {
			m.Write(&sb)
		}
	}

	fmt.Println(sb.String())

}

Before

go run foo/foo.go
I0414 15:19:35.573271   76061 custom_resource_metrics.go:79] "Custom resource state added metrics" familyNames=[kube_customresource_gauge kube_customresource_info]
kube_customresource_gauge
{active="1",customresource_group="myteam.io",customresource_kind="Foo",customresource_version="v1",type="type-a"} 2
{active="3",customresource_group="myteam.io",customresource_kind="Foo",customresource_version="v1",type="type-b"} 4
kube_customresource_info
{customresource_group="myteam.io",customresource_kind="Foo",customresource_version="v1",type="type-a"} 1
{customresource_group="myteam.io",customresource_kind="Foo",customresource_version="v1",type="type-b"} 1

After

go run foo/foo.go
I0414 17:18:39.914212   92158 custom_resource_metrics.go:79] "Custom resource state added metrics" familyNames=[kube_customresource_gauge kube_customresource_info]
kube_customresource_gauge
{active="1",customresource_group="myteam.io",customresource_kind="Foo",customresource_version="v1",type="type-a"} 2
{active="3",customresource_group="myteam.io",customresource_kind="Foo",customresource_version="v1",type="type-b"} 4
kube_customresource_info
{active="1",customresource_group="myteam.io",customresource_kind="Foo",customresource_version="v1",type="type-a"} 1
{active="3",customresource_group="myteam.io",customresource_kind="Foo",customresource_version="v1",type="type-b"} 1

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: murphd40 (f94a001, b63b413)

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[dgrisonnet]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dgrisonnet, murphd40

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[dgrisonnet]

@murphd40 thank for contributing the fix and adding a unit test! :)