Remove Contrib from namespaces and package names

[askpt]

We need to remove "contrib" from all package names and namespaces across this repository. This change is necessary to standardise naming conventions and align with current OpenFeature guidelines.

Tasks:

• [ ] Update package names to remove any reference to "contrib".
• [ ] Refactor all namespaces in the codebase to exclude "contrib".
• [ ] Update documentation, build scripts, and any references in CI/CD pipelines to use the new package names and namespaces.
• [ ] Update tests
• [ ] Ensure that any published packages and NuGet configuration are updated accordingly.
• [ ] Double-check for references in tests, examples, and README files.
• [ ] Provide migration notes or guidance if this change requires consumers to update their dependencies or imports.