Adding Windows Overlay support to Kube Proxy

[ksubrmnn]

What type of PR is this?

Uncomment only one, leave it on its own line:

/kind api-change
/kind bug
/kind cleanup
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:
This PR adds support in Kube-proxy for Overlay networks in Windows. Kube-Proxy currently only supports L2Bridge networks on Windows. On Windows, Host Networking Service (HNS) is responsible for ensuring network connectivity. HNS needs to be programmed in a different way for Overlay than L2Bridge.

Specifically, HNS needs additional configuration to allow Cluster IP connectivity. This is reflected in this PR by programming "service VIPs."

Currently HNS supports both DSR and non DSR for loadbalancing. This support is also reflected in this PR by adding support for both.

This PR also adds support for using HNS in V1 and V2. V2 is necessary for DSR and Overlay, but non DSR L2Bridge is supported in both.

Testing:
Basic unit tests for Kube Proxy are added in this PR to check if remote endpoints and loadbalancers are created and accounted for. More testing will follow in subsequent PRs.

Tests were also created to test HNS V1 and V2 implementations that were added in this PR.
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 #

Special notes for your reviewer:
This is an Alpha feature
There is no design doc associated with this feature
Hcsshim was updated to include the RemoteSubnetPolicy API changes

Does this PR introduce a user-facing change?:

Added kube-proxy support for overlay networking and DSR in Windows and new flags for network-name, source-vip, and enable-dsr.

[k8s-ci-robot]

Hi @ksubrmnn. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[ksubrmnn]

/assign @thockin

[thockin]

Can you please update the first comment in this PR to include more information? A lot more.

What does this do? Pretend I don't know anything about Windows.

Was there a design doc or KEP?

Is it considered Alpha or Beta or GA?

Where are the tests? That's a LOT of code to add with no tests.

What should the release notes say about this?

I can't do meaningful review of it because I really don't know what it is doing.

[madhanrm]

/lgtm

[madhanrm]

/lgtm

[madhanrm]

@thockin can you please take a look at this PR and help us get this merged? We have several follow up PRs on top of this one.

[dineshgovindasamy]

@thockin following up from the sig/network meeting, Could you please take a look at this PR and provide your feedback or approve the PR?

[ksubrmnn]

@thockin I've separated out the Windows only code into commit b724bdb.

You only need to look at the first 3 commits and the last one. I believe you've already looked at the first 3 so only the last one is new and includes the feature flags.

[thockin]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ksubrmnn, madhanrm, thockin

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• Godeps/OWNERS [thockin]
• cmd/OWNERS [thockin]
• pkg/proxy/apis/config/OWNERS [thockin]
• pkg/proxy/winkernel/OWNERS [madhanrm,thockin]
• staging/src/k8s.io/apiserver/pkg/features/OWNERS [thockin]
• staging/src/k8s.io/kube-proxy/config/OWNERS [thockin]
• vendor/OWNERS [thockin]

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