Handle terminal errors in AzureCluster controller

[sayantani11]

What type of PR is this?

What this PR does / why we need it:

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 #1973

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:

Handle terminal errors in AzureCluster controller

[sonasingh46]

Question: Are terminal errors applicable only for AzureCluster and AzureMachine controller? May be out of scope of this PR but if applicable we can consider adding them too as a followup. Will need to check on wether it is applicable or not.
cc @Jont828 @CecileRobertMichon

[CecileRobertMichon]

Question: Are terminal errors applicable only for AzureCluster and AzureMachine controller. May be out of scope of this PR but if applicable we can consider adding them too as a followup. Will need to check on wether it is applicable or not.

Agreed, but since this is a good-first-issue PR let's keep the original scope of just AzureCluster controller.

[jackfrancis]

/lgtm

[CecileRobertMichon]

/approve

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