feat: hook execution lifecycle

[NeaguGeorgiana23]

This PR

• Implements the complete OpenFeature Hook Execution Lifecycle in ClientAPIaccording to Section 4 of the OpenFeature specification.
• Introduces HookSupport to encapsulate hook aggregation and stage execution helpers:
  • CollectHooks: Aggregates hooks across API, Client, Invocation, and Provider tiers in FIFO precedence order while filtering out nullptr entries.
  • CreateHookDataMap: Creates HookData instances per unique hook to persist stage data across an evaluation.
  • ExecuteBeforeHooks: Executes before hooks in forward order (API $\to$ Client $\to$ Invocation $\to$ Provider), supporting evaluation context mutation and error short-circuiting.
  • ExecuteAfterHooks: Executes after hooks in reverse order (Provider $\to$ Invocation $\to$ Client $\to$ API), transforming the result into error details if a hook throws.
  • ExecuteErrorHooks: Executes error hooks in reverse order upon abnormal execution (in before, resolution, or after stages), catching and suppressing exceptions per Requirement 4.4.4.
  • ExecuteFinallyHooks: Unconditionally executes finally hooks in reverse order, catching and suppressing exceptions per Requirement 4.4.3.
• Adds const T* GetAs(const std::string& key) const overload to HookData for const-safe access to stored hook state.
• Updates ClientAPI::EvaluateFlag evaluate flags cleanly via HookSupport.
• Adds unit tests in test/client_api_test.cpp and test/hook_data_test.cpp covering hook execution order, hint propagation, type filtering, exception handling, and provider lifecycle status routing (kNotReady, kFatal, kError, kStale).

Related Issues

Fixes #135

Notes

• Hook execution conforms to OpenFeature evaluation rules (Requirement 4.4.2), running before hooks from least specific to most specific (API $\to$ Client $\to$ Invocation $\to$ Provider) and after/error/finally in reverse order.
• In accordance with Requirements 4.4.3 and 4.4.4, any exceptions thrown inside error or finally hooks are safely caught and swallowed to guarantee evaluation completes.

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