Make public IPs 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 public IPs as a follow up for #1610 and #1541. Thanks to @karuppiah7890 for starting this effort!

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 #1716

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 public IPs reconcile/delete async

[netlify]

👷 Deploy request for kubernetes-sigs-cluster-api-provider-azure pending review.

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Name	Link
🔨 Latest commit	4efef06

[Jont828]

/assign @CecileRobertMichon

[CecileRobertMichon]

@Jont828 could you please rebase this one?

Is it ready for review?

[Jont828]

@CecileRobertMichon Yep, I rebased and this should be ready for review!

[Jont828]

@CecileRobertMichon @jackfrancis I removed the public IP client interface and updated it in the VM service as well. PTAL when you have some time. Thanks!

[CecileRobertMichon]

One more comment about making the AzureClient unexported, otherwise LGTM

please squash commits

[CecileRobertMichon]

/lgtm
/approve

[CecileRobertMichon]

/retest

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 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	ced144c	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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