[Python] Add AI link to Azure packages readme

[lmazuel]

For all Azure packages, the default readme should now include this:

### Use with AI tools

AI coding tools such as VS Code and GitHub Copilot can help you write and debug code that uses this library. See [Using the Azure SDK for Python with AI tools](https://aka.ms/azsdk/python/ai) for available integrations.

For example of where in the Readme put it, see this PR for details:
https://github.com/Azure/azure-sdk-for-python/pull/46294/changes