Added an example to show how to use api_client to make generic api calls.

[harrydu-db]

What changes are proposed in this pull request?

I am adding one example under examples. It is to demonstrate how to use api_client for making generic REST API calls. This serves as an example for users who need to interact with REST endpoints that are not yet wrapped by the Python SDK.

NO_CHANGELOG=true

How is this tested?

• make test run locally
• make fmt applied
• relevant integration tests applied

[github-actions]

If integration tests don't run automatically, an authorized user can run them manually by following the instructions below:

Trigger:
go/deco-tests-run/sdk-py

Inputs:

• PR number: 949
• Commit SHA: 73956ce574375e3796da225606bc7cdb64a3f3f4

Checks will be approved automatically on success.

[renaudhartert-db]

The API client is actually not meant to be used directly and will likely become private in the future. The Databricks SDK aims to offer clients for all public Databricks API. If one API is not included, then it's probably due to an upstream issue that we need to resolve internally. Please feel free to reach out internally for more details.