Isolate Hook dependencies: Create OpenFeature.Hooks.Abstractions library

[askpt]

Requirements

Propose the creation of a new library: OpenFeature.Hooks.Abstractions within the .NET ecosystem. This library should contain only the essential dependencies for Hooks, thereby isolating them from SDK churn and potential breaking changes.

Rationale:

• By extracting hook-related abstractions and dependencies into their own library, developers who implement Hooks will not be impacted by unrelated SDK updates or changes.
• This improves stability for hook developers, provides clearer boundaries, and supports easier versioning and maintenance of hook contracts.
• The new library should depend only on what is required for hook functionality. Avoid including SDK-level dependencies.

Requirements:

• Define and document the core abstractions and interfaces needed for Hooks.
• Move or replicate only the necessary code from the main SDK to this library.
• Update documentation to explain the separation and usage.
• Prepare for package publishing and adoption recommendations.

Goal:

• Isolate the Hooks abstraction from SDK churn, simplify maintenance, and clarify dependency boundaries.