fix: Change registration to use the Isolated API instead of global singleton

[askpt]

This PR

This pull request updates how the OpenFeature API instance is registered within the dependency injection container. Instead of registering the global Api.Instance, it now registers an isolated API instance using OpenFeatureFactory.CreateIsolated(). This ensures that all components in the application share the same isolated instance, allowing for better lifecycle management and isolation from global state.

Dependency injection and API registration:

• Replaced registration of the global Api.Instance singleton with an isolated API instance created by OpenFeatureFactory.CreateIsolated() in AddOpenFeature to ensure application-wide isolation and improved lifecycle management.
• Added using OpenFeature.Isolated; to support the creation of isolated API instances.

Related Issues

Fixes #759

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.52%. Comparing base (5623a0f) to head (f7cac98).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #760   +/-   ##
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  Coverage   93.52%   93.52%           
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  Files          69       69           
  Lines        2981     2981           
  Branches      355      355           
=======================================
  Hits         2788     2788           
  Misses        135      135           
  Partials       58       58           

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[gemini-code-assist]

Code Review

This pull request updates the OpenFeature service registration to use an isolated API instance instead of the global singleton. Feedback suggests using a factory delegate for the singleton registration to avoid unnecessary object allocation and recommends shortening the verbose warning suppression comment for better readability.

[gkinsman]

Thanks for fixing this!

[im-aIex]

any estimate on when this fix will be published?

[askpt]

any estimate on when this fix will be published?

@im-aIex hey! I'm waiting on this PR #755. As soon as it gets merged, I will release a new version.