feat: add azure ad workload identity support

[jeffpuckett]

Description

Add support for Azure AD Workload Identity. https://learn.microsoft.com/en-us/azure/aks/workload-identity-overview

Fixes: <! -- link to issue -->

Checklist

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Type of Change

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• New tests
• Build/CI related changes
• Documentation content changes
• Other (please describe)

Other information

First time writing Golang, but I'm gonna figure it out.

A couple of things to note

• I don't often code and I wouldn't know how to test an authentication callback so that is not implemented. Any advice would be appreciated.
• Further work will be needed as the current sdk being used is unsupported as of march of 2023. For now, having the functionality work at all is very helpful.
• I haven't figured out how to pass environment variables from config.go to a callback in another file, and I figure the callback should be in another file. Comments welcome, but for now I am getting the environment variables in the authentication callback. Of note the environment variables are added to any pod configured to work with workload identity.

[CLAassistant]

All committers have signed the CLA.

[YvesZelros]

I write a new PR on the same subject but that use azidentity.NewDefaultAzureCredential that support natively follow Azure auth methods

The following credential types if enabled will be tried, in order:

• EnvironmentCredential
• WorkloadIdentityCredential
• ManagedIdentityCredential
• SharedTokenCacheCredential

[werne2j]

Closing in favor of #548