Make inbound NAT rules reconcile/delete async

[Jont828]

What type of PR is this?

/kind feature
What this PR does / why we need it: Implementation of an async service for inbound NAT rules as a follow up for #1610 and #1541.

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 #1712

Special notes for your reviewer:

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Make inbound NAT rules reconcile/delete async

[k8s-ci-robot]

Hi @Jont828. Thanks for your PR.

I'm waiting for a kubernetes-sigs 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.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[CecileRobertMichon]

/ok-to-test

[CecileRobertMichon]

lgtm

/assign @mboersma

[devigned]

Code / tests look solid. Nice work!

lgtm

[CecileRobertMichon]

/lgtm
/approve

🎉

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CecileRobertMichon

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• OWNERS [CecileRobertMichon]

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[k8s-ci-robot]

@Jont828: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-provider-azure-apidiff	8bd2880	link	false	/test pull-cluster-api-provider-azure-apidiff

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[CecileRobertMichon]

/lgtm

[Jont828]

Let's go!!!