Adds AKV Token Binding Managed Identity E2E tests

[gladjohn]

This pull request extends the managed identity tests to include support for Azure Key Vault (AKV) mTLS Proof-of-Possession (PoP) token acquisition and resource calls with attestation. It also refactors existing tests to use more descriptive resource constants and adds a helper method for AKV secret retrieval.

AKV mTLS PoP Testing Enhancements:

• Added a new test method AcquireTokenAndCallAKV_OnImdsV2_MtlsPoP_WithAttestation_Succeeds to validate mTLS PoP token acquisition and AKV secret retrieval with attestation, including certificate validation and proper error handling.

• Introduced the CallAkvSecretAsync helper method to perform authenticated mTLS calls to the AKV secret endpoint, asserting successful response and secret value presence.

Resource Constant Refactoring:

• Replaced the generic ArmScope constant with more descriptive GraphResource, AkvResource, and AkvSecretUrl constants for improved clarity and maintainability in test setup.

• Updated existing tests to use the new GraphResource constant instead of ArmScope for managed identity token acquisition. [1] [2]

Imports Organization:

• Reordered and grouped using statements for better readability and to support new AKV test functionality.

[Copilot]

Pull request overview

This PR expands the IMDSv2 Managed Identity E2E test suite to validate Azure Key Vault (AKV) mTLS Proof-of-Possession (PoP) token acquisition and an authenticated AKV secret retrieval call using Credential Guard attestation. It also refactors resource constants for clarity.

Changes:

• Added an AKV E2E test that acquires an attested mTLS PoP token and calls an AKV secret endpoint using the binding certificate.
• Introduced an CallAkvSecretAsync helper to perform the token-bound mTLS HTTP call and validate the JSON response.
• Renamed/refactored resource constants (ArmScope → GraphResource, plus new AkvResource/AkvSecretUrl) and reorganized using directives.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 3 comments.

[RyAuld]

Confirmed KV resource is setup correctly.