…eatureClient is unresolvable (#157)

### Overview

This pull request refactors the client creation logic in
`OpenFeatureAPI` to improve testability and resilience.

- Introduces a dedicated `resolveClient` method, which encapsulates
client instantiation logic.

- Ensures that failures during client resolution are handled gracefully
by returning a `NoOpClient`.

- Adds a testing dependency to allow mocking of final classes, enabling
comprehensive test coverage without altering production code.

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Signed-off-by: tmakinde <[email protected]>

Change log message to follow best practice of PSR3, Log Exception object
to help debuging, when provider throw Exception

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## This PR
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- Improve the log message and context, when the OpenFeatureClient catch
Exception

### Related Issues
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### Notes
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### Follow-up Tasks
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noted under this section -->
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### How to test
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- Unit test updated to test the changes

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Signed-off-by: jaugustin <[email protected]>

🤖 I have created a release *beep* *boop*
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##
[2.1.0](2.0.12...2.1.0)
(2025-09-14)


### ✨ New Features

* **log:** Improve error log in OpenFeatureClient
([#156](#156))
([d28d9c3](d28d9c3))

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