Microsoft.FeatureManagement provides standardized APIs for enabling feature flags within applications. Utilize this library to secure a consistent experience when developing applications that use patterns such as beta access, rollout, dark deployments, and more.
According to #376
BTW, all AppConfig SDK public APIs made the CancellationToken optional: https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/appconfiguration/Azure.Data.AppConfiguration/src/ConfigurationClient.cs
This PR makes cancellation token optional for async methods of IVariantFeatureManager and adds cancellation token to async methods of ISessionManager