Add async callback support to TrustList implementation

[Copilot]

Proposed changes

The TrustList class only supported synchronous OnCall callbacks, forcing async operations to block with .GetAwaiter().GetResult(). This adds native async support via OnCallAsync handlers while maintaining backward compatibility.

Following feedback from @romanett, the implementation uses async as the core with sync wrappers, rather than separate sync and async implementations.

Key changes:

• Async methods are the core implementation (OpenCoreAsync, ReadAsync, WriteAsync, CloseAsync, CloseAndUpdateAsync, AddCertificateAsync, RemoveCertificateAsync)
• Sync methods are lightweight wrappers that call .AsTask().ConfigureAwait(false).GetAwaiter().GetResult() on async core
• Both sync and async callbacks registered in constructor - generated code automatically prefers async when available
• Replaced blocking .GetAwaiter().GetResult() patterns in async code paths with proper await and ConfigureAwait(false)
• Proper CancellationToken propagation throughout all async operations
• Helper methods (UpdateStoreCertificatesAsync, UpdateStoreCrlsAsync) updated to accept and propagate CancellationToken

Implementation pattern:

// Constructor registers both callbacks
node.Open.OnCall = new OpenMethodStateMethodCallHandler(Open);
node.Open.OnCallAsync = new OpenMethodStateMethodAsyncCallHandler(OpenAsync);

// Sync wrapper calls async core with ConfigureAwait(false)
private ServiceResult Open(..., ref uint fileHandle)
{
    var result = OpenAsync(..., CancellationToken.None)
        .AsTask().ConfigureAwait(false).GetAwaiter().GetResult();
    fileHandle = result.FileHandle;
    return result.ServiceResult;
}

// Async core uses proper await
private async ValueTask<OpenMethodStateResult> OpenCoreAsync(...)
{
    X509Certificate2Collection certificates = await store.EnumerateAsync(cancellationToken)
        .ConfigureAwait(false);
    // Process certificates...
}

Types of changes

• Enhancement (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING doc.
• I have signed the CLA.
• I ran tests locally with my changes, all passed.
• I fixed all failing tests in the CI pipelines.
• I fixed all introduced issues with CodeQL and LGTM.
• I have added tests that prove my fix is effective or that my feature works and increased code coverage.
• I have added necessary documentation (if appropriate).
• Any dependent changes have been merged and published in downstream modules.

Further comments

The implementation follows an async-core pattern where:

• Async methods contain the actual implementation logic using proper await
• Sync methods are thin wrappers using .AsTask().ConfigureAwait(false).GetAwaiter().GetResult() to prevent deadlocks
• Stream operations (Read/Write) return ValueTask directly for efficiency since MemoryStream operations are inherently synchronous
• All async certificate store operations properly propagate CancellationToken for proper cancellation support

This approach provides clean async code paths while maintaining full backward compatibility for existing code using sync callbacks.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Server] Make default TrustList Implemenation support async Callback OnCallAsync in addtion to OnCall</issue_title>
<issue_description>The default TrustList implementation in the Server Library should use the native Callbacks to Async code present in the generated classes (OnCallAsync). To not break users still relying on the sync callbacks the TrustList class shall be extended to support both the Sync Callbacks and Async callbacks ensuring proper usage of async Code.

</issue_description>

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

• Fixes [Server] Make default TrustList Implemenation support async Callback OnCallAsync in addtion to OnCall #3482

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[romanett]

@copilot instead of adding completely new async versions update the internals of the sync version to be async and make a sync wrapper using the .AsTask().GetAwaiter().GetResult() pattern.

[Copilot]

@copilot instead of adding completely new async versions update the internals of the sync version to be async and make a sync wrapper using the .AsTask().GetAwaiter().GetResult() pattern.

Refactored the implementation as requested. The async methods are now the core implementation, and sync methods wrap them using .AsTask().GetAwaiter().GetResult(). Both OnCall and OnCallAsync handlers are registered. Changes in commit 714b4ea.