[feature request] Support a SidecarSet canary on a newly created pod with version control for injection and selector

[amirakhmedov]

What would you like to be added:
Add support for a SidecarSet canary on a newly created pod with a canary labels set using version control for injection and selector.

Why is this needed:
I want to use the combination of the two to canary a new version of a sidecar on pods with a canary label attached. This will guarantee that newly created pods will get injected a stable version of the sidecar. It works fine if only in-place update is possible. But if in-place update is impossible, let's say a canary version requires a new env variable to be added, then a newly created pod with a canary label set on it still gets injected a stable version of the sidecar.
I would like to see a mutating webhook to take into consideration .spec.updateStrategy.selector to make a decision which version of a SidecarSet (stable or canary) to use.