Merge pull request #46580 from Huawei-PaaS/kube-proxy-ipvs-pr

Automatic merge from submit-queue (batch tested with PRs 51377, 46580, 50998, 51466, 49749)

Implement IPVS-based in-cluster service load balancing

**What this PR does / why we need it**:

Implement IPVS-based in-cluster service load balancing. It can provide some performance enhancement and some other benefits to kube-proxy while comparing iptables and userspace mode. Besides, it also support more sophisticated load balancing algorithms than iptables (least conns, weighted, hash and so on).

**Which issue this PR fixes**

#17470 #44063

**Special notes for your reviewer**:


* Since the PR is a bit large, I splitted it and move the commits related to ipvs util pkg to PR #48994. Hopefully can make it easier to review.

@thockin @quinton-hoole @kevin-wangzefeng @deepak-vij @haibinxie @dhilipkumars @fisherxu 

**Release note**:

```release-note
Implement IPVS-based in-cluster service load balancing
```

pkg/features/kube_features.go

@@ -127,6 +127,12 @@ const (
 	// Taint nodes based on their condition status for 'NetworkUnavailable',
 	// 'MemoryPressure', 'OutOfDisk' and 'DiskPressure'.
 	TaintNodesByCondition utilfeature.Feature = "TaintNodesByCondition"
+
+	// owner: @haibinxie
+	// alpha: v1.8
+	//
+	// Implement IPVS-based in-cluster service load balancing
+	SupportIPVSProxyMode utilfeature.Feature = "SupportIPVSProxyMode"
 )
 
 func init() {
@@ -164,4 +170,5 @@ var defaultKubernetesFeatureGates = map[utilfeature.Feature]utilfeature.FeatureS
 	// inherited features from apiextensions-apiserver, relisted here to get a conflict if it is changed
 	// unintentionally on either side:
 	apiextensionsfeatures.CustomResourceValidation: {Default: false, PreRelease: utilfeature.Alpha},
+	SupportIPVSProxyMode:                           {Default: false, PreRelease: utilfeature.Alpha},
 }