Automatic merge from submit-queue (batch tested with PRs 48981, 47316, 49180)
azure: acr: support MSI with preview ACR with AAD auth
**What this PR does / why we need it**:
The recently added support for Managed Identity in Azure (#48854) was incompatible with automatic ACR docker credential integration (#48980).
This PR resolves that, by leveraging a feature available in Preview regions, on new managed clusters with support for AAD `access_token` authentication.
Notes:
* This includes code copied from [Azure/acr-docker-credential-helper](https://github.com/Azure/acr-docker-credential-helper). I copied the MIT license from that project and added a copyright line for Microsoft on it. (but one of the hack/verify-* scripts requires the Kubernetes copyright header. So there are two copyright headers in the file now...)
* Eventually this should vendor [Azure/acr-docker-credential-helper](https://github.com/Azure/acr-docker-credential-helper) when it exposes the right functionality.
* This includes a small, non-function-impacting workaround for a temporary service-side bug.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#48980
**Special notes for your reviewer**:
Please don't LGTM it without reviewing the `azure_acr_helper.go` file's license header...
**Release note**:
```release-note
azure: acr: support MSI with preview ACR with AAD auth
```
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