🐛 Ensure MachineSet controller won't orphan resources

[zjs]

What this PR does / why we need it:

To ensure that the MachineSet controller won't orphan infrastructure config or bootstrap config resources as the result of an incomplete reconcile followed by cluster deletion, add an OwnerReference during creation of these resources by the MachineSet controller.

This case may be uncommon when Cluster API is used directly by a user (as the window where deletion of the Cluster will lead to an orphaned resource is short), but may be more common when an automation layer sits above Cluster API (as its "reaction time" may be fast).

Which issue(s) this PR fixes:

I didn't file a separate issue for this, but would be happy to do so.

Additional details:

I borrowed pieces of this change from #1959 on master, introducing a new method that supports passing owners to avoid backwards-compatibility issues (because CloneTemplate is a public function and I'm proposing submission to a release branch).

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[k8s-ci-robot]

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[randomvariable]

/ok-to-test

[randomvariable]

/ok-to-test

[randomvariable]

Seems reasonable. That's an LGTM from me.

[vincepri]

/lgtm

[vincepri]

@ncdc over to you for approval

[ncdc]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ncdc, zjs

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