PR Summary

This pull request includes several changes to improve the handling and testing of unauthenticated access tokens for container registries. The most important changes include updating token templates, modifying access token retrieval logic, and adding new tests for unauthenticated repositories.

Improvements to token handling:

• src/code/ContainerRegistryServerAPICalls.cs: Updated the containerRegistryAccessTokenTemplate to include registry:catalog:* scope and added a new defaultScope constant.

Modifications to access token retrieval logic:

• src/code/ContainerRegistryServerAPICalls.cs: Modified the GetContainerRegistryAccessToken method to retrieve and return an anonymous access token if available. [1] [2]
• src/code/ContainerRegistryServerAPICalls.cs: Updated the IsContainerRegistryUnauthenticated method to check for an authentication challenge header and retrieve an anonymous access token if present.

Code simplification:

• src/code/ContainerRegistryServerAPICalls.cs: Simplified the FindPackages method to handle repository names with and without the psresource/ prefix.

Testing improvements:

• test/FindPSResourceTests/FindPSResourceContainerRegistryServer.Tests.ps1: Modified a test to ensure all resources are found given the name *.
• test/FindPSResourceTests/FindPSResourceContainerRegistryServer.Tests.ps1: Added a new test for finding resources in an unauthenticated ACR repository.

PR Context

Unauthenticated ACR other than MCR respond with an auth challenge to acquire an anonymous token. This token is required for further operations.

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