Make virtual network peerings 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 virtual network peerings 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 #1829

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 virtual network peerings 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.

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[CecileRobertMichon]

/ok-to-test

[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	0579d71	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.

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[CecileRobertMichon]

/lgtm
/assign @mboersma

[mboersma]

/lgtm

[CecileRobertMichon]

One thing that @Jont828 and I discussed offline that we should look into is how we can omit conditions when they don't apply to a specific AzureCluster. For example, if we set VnetPeeringsReady to true, it implies that there are vnet peerings in the cluster and that they are ready. However, currently, that is not the case since if there are 0 resources of that type, the condition will still be set to true so that it doesn't block the overall Ready status. @Jont828 it would be good to open an issue for this so we can brainstorm ideas.

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CecileRobertMichon

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