Automatic merge from submit-queue (batch tested with PRs 61400, 61048). 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>.
code-gen: allow specifying custom resync periods for certain informer types
**What this PR does / why we need it**:
This PR extends the informer code-generator to allow the consumer to specify a custom resync period for certain informer types and uses the default resync period if none is defined.
**Special notes for your reviewer**:
Example:
```go
cs := clientset.NewForConfigOrDie(config)
resyncConfig := externalversions.ResyncConfiguration{
&samplev1alpha1.Sample{}: 30 * time.Second,
}
informer := externalversions.NewSharedInformerFactory(cs, 2*time.Minute, externalversions.WithCustomResyncConfig(resyncConfig))
```
**Release note**:
```release-note
NONE
```
Kubernetes-commit: 7daaa826d291c1501a52177c3e14b00c503c8527
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>.
Remove YEAR field of all generated files and fix kubernetes boilerplate checker
**What this PR does / why we need it**:
Remove YEAR field of all generated files and fix kubernetes boilerplate checker
xref: [remove YEAR fileds in gengo #91](https://github.com/kubernetes/gengo/pull/91)
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes [#gengo/issues/24](https://github.com/kubernetes/gengo/issues/24)
**Special notes for your reviewer**:
/cc @thockin @lavalamp @sttts
**Release note**:
```release-note
NONE
```
Kubernetes-commit: e40ffd71972b820aeed283946e880aa2479f8524
