Add OpenFeature library for feature flag management

[askpt]

Feature management/OpenFeature - OpenFeature

OpenFeature is an open standard for feature flag management that enables developers to standardize feature flagging across different tools and platforms. It provides a unified API and SDKs for multiple programming languages, allowing users to decouple feature flag evaluation from vendor-specific implementations. OpenFeature promotes interoperability, flexibility, and standardization, simplifying the integration process and reducing vendor lock-in.

For more details, visit the .NET SDK repository to explore the core SDK and its capabilities.