[enhancement] enable yurthub to handle upgrade request

[Congrool]

What type of PR is this?

/kind enhancement

What this PR does / why we need it:

Since APIServer can handle websocket request, yurthub which is serving as a proxy server for kubelet and other components should have the capability of proxying websocket traffic to APIServer.

Which issue(s) this PR fixes:

Fixes #562

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

[Congrool]

I've rerun the failed conformance cases in #562, and all cases passed.

Here's also some websocket request logs.

WSAPISERVER=wss://169.254.2.1:10268
SECRET_NAME=log-exporter-sa-token-jkqlt
TOKEN=$(kubectl get secret $SECRET_NAME -o jsonpath='{.data.token}' | base64 --decode)
wscat -n -c $WSAPISERVER/api/v1/namespaces/kube-system/pods/yurt-tunnel-agent-cssqz/log?container=yurt-tunnel-agent --header "Authorization: Bearer $TOKEN"

We can see that the proxy of websocket request succeeded.

[openyurt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Congrool, rambohe-ch

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• OWNERS [rambohe-ch]

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[rambohe-ch]

@Congrool Based on this pull request, kubectl exec can work or not through yurthub?

[rambohe-ch]

/hold

[Congrool]

@rambohe-ch
It seems no problem. I followed the step in #562, running kubectl exec into the pod called sonobuoy-e2e-job-cb02e5e67e844d4f. Here's the log.

As mentioned in the #562, the problem has been solved by #560.

[rambohe-ch]

/hold cancel

[rambohe-ch]

@Congrool This issue #638 is also solved. @DrmagicE

[rambohe-ch]

@DrmagicE Do you have any comments about this pull request?

[DrmagicE]

/lgtm