There should be a c interface to set client current language.

**BUG REPORT**

1. Please describe the issue you observed:

- What did you do (The steps to reproduce)?

By using Python SDK, we found that the language of client in console was still "CPP".

- What did you expect to see?

Using Python SDK, the language of client should be "PYTHON".

- What did you see instead?


Start from the Python SDK entry point that creates the client and trace how the client language is represented in the C++ client. Add the missing C-facing way to set that language, then verify that a client created through the Python SDK is reported as "PYTHON" rather than "CPP" in the console.

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