Automatic merge from submit-queue (batch tested with PRs 46550, 46663, 46816, 46820, 46460)

[GCE] Support internal load balancers

**What this PR does / why we need it**:
Allows users to expose K8s services externally of the K8s cluster but within their GCP network. 

Fixes #33483

**Important User Notes:**
- This is a beta feature. ILB could be enabled differently in the future. 
- Requires nodes having version 1.7.0+ (ILB requires health checking and a health check endpoint on kube-proxy has just been exposed)
- This cannot be used for intra-cluster communication. Do not call the load balancer IP from a K8s node/pod.  
- There is no reservation system for private IPs. You can specify a RFC 1918 address in `loadBalancerIP` field, but it could be lost to another VM or LB if service settings are modified.
- If you're running an ingress, your existing loadbalancer backend service must be using BalancingMode type `RATE` - not `UTILIZATION`. 
  - Option 1: With a 1.5.8+ or 1.6.4+ version master, delete all your ingresses, and re-create them.
  - Option 2: Migrate to a new cluster running 1.7.0. Considering ILB requires nodes with 1.7.0, this isn't a bad idea.
  - Option 3: Possible migration opportunity, but use at your own risk. More to come later.


**Reviewer Notes**:
Several files were renamed, so github thinks ~2k lines have changed. Review commits one-by-one to see the actual changes.

**Release note**:
```release-note
Support creation of GCP Internal Load Balancers from Service objects
```