Kh add rule detect ephemeral container

[Kaizhe]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

If contributing rules or changes to rules, please make sure to also uncomment one of the following line:

/kind rule-update

/kind rule-create

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area build

/area engine

/area rules

/area tests

/area proposals

What this PR does / why we need it:
Create a new rule to detect ephemeral container is created in a pod.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:
https://kubernetes.io/docs/concepts/workloads/pods/ephemeral-containers/
Audit log:

{"kind":"Event","apiVersion":"audit.k8s.io/v1","level":"Request","auditID":"b1737080-a7fd-44c5-87b5-3777dcf493c4","stage":"ResponseComplete","requestURI":"/api/v1/namespaces/default/pods/ubuntu-2/ephemeralcontainers","verb":"update","user":{"username":"admin","uid":"admin","groups":["system:masters","system:authenticated"]},"sourceIPs":["98.207.36.92"],"userAgent":"kubectl/v1.18.6 (darwin/amd64) kubernetes/dff82dc","objectRef":{"resource":"pods","namespace":"default","name":"ubuntu-2","apiVersion":"v1","subresource":"ephemeralcontainers"},"responseStatus":{"metadata":{},"code":200},"requestObject":{"kind":"EphemeralContainers","apiVersion":"v1","metadata":{"name":"ubuntu-2","creationTimestamp":null},"ephemeralContainers":[{"name":"debugger","image":"busybox","command":["sleep","3600"],"resources":{},"terminationMessagePolicy":"File","imagePullPolicy":"IfNotPresent","stdin":true,"tty":true}]},"requestReceivedTimestamp":"2020-07-31T21:45:48.728559Z","stageTimestamp":"2020-07-31T21:45:48.736514Z","annotations":{"authorization.k8s.io/decision":"allow","authorization.k8s.io/reason":""}}

Does this PR introduce a user-facing change?:

rule(EphemeralContainers Created): add new rule to detect ephemeral container created

[leogr]

LGTM,

thanks!

[poiana]

LGTM label has been added.

Git tree hash: 8d68ee9080ab1dad77f6378f251505a77a90dffa

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: leogr, mstemm

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• rules/OWNERS [leogr,mstemm]

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