Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Make feature gates loadable from a map[string]bool
Command line flag API remains the same. This allows ComponentConfig
structures (e.g. KubeletConfiguration) to express the map structure
behind feature gates in a natural way when written as JSON or YAML.
For example:
KubeletConfiguration Before:
```
apiVersion: kubeletconfig/v1alpha1
kind: KubeletConfiguration
featureGates: "DynamicKubeletConfig=true,Accelerators=true"
```
KubeletConfiguration After:
```
apiVersion: kubeletconfig/v1alpha1
kind: KubeletConfiguration
featureGates:
DynamicKubeletConfig: true
Accelerators: true
```
Fixes: #53024
```release-note
The Kubelet's feature gates are now specified as a map when provided via a JSON or YAML KubeletConfiguration, rather than as a string of key-value pairs.
```
/cc @mikedanese @jlowdermilk @smarterclayton