[DRAFT] Pure MSI mTLS code + DevApp

[gladjohn]

This pull request introduces support for mTLS Proof-of-Possession (PoP) with attestation for managed identity token acquisition, and adds a new sample app demonstrating this feature. The main changes include updating dependencies, modifying token acquisition logic, and adding a new test application with configuration and documentation.

Dependency updates and token acquisition enhancements:

• Added Microsoft.Identity.Client.KeyAttestation as a dependency in Directory.Build.props and Microsoft.Identity.Web.TokenAcquisition.csproj to enable attestation support. [1] [2] [3]
• Updated TokenAcquisition.cs to use Microsoft.Identity.Client.KeyAttestation and to enable mTLS PoP and attestation when the IsTokenBinding option is set. [1] [2]

Sample app additions for demonstration:

• Added a new project daemon-app-msi-v2 to the solution, including project file, source code, configuration, and documentation. [1] [2] [3] [4]
• Implemented Program.cs for the sample app, showing how to use managed identity with attestation to retrieve a Key Vault secret.
• Provided appsettings.json for the sample app, including configuration for managed identity, Key Vault access, and enabling mTLS PoP with attestation.
• Added a readme.md explaining prerequisites and the flow of the sample app.

Up Next:

• Unit test for Pure MSI mTLS POP
• FIC MSI with mTLS POP (Code + Unit tests)