[WIP] Refine tokenFile write logic to enhance security

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

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This section details on the original issue you should resolve

<issue_title>refine tokenFile write logic</issue_title>
<issue_description>

blob-csi-driver/pkg/blob/blob.go

Line 601 in 1f8185b

azureOAuthTokenFile := filepath.Join(defaultAzureOAuthTokenDir, clientID+accountName)

The file path is constructed by directly concatenating clientID and accountName without any sanitization or validation. If clientID contains path traversal characters like "../" or if it's empty, this could lead to unexpected file paths issues. Consider validating clientID for invalid characters or using a safer path construction method like filepath.Clean() after ensuring clientID is non-empty.

What happened:

What you expected to happen:

How to reproduce it:

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Environment:

• CSI Driver version:
• Kubernetes version (use kubectl version):
• OS (e.g. from /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Others:
  </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes refine tokenFile write logic #2272

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