Add /ping endpoint

[wjdp]

No description provided.

[Copilot]

Pull Request Overview

This PR adds a /ping endpoint to the API for testing API key authentication and basic connectivity. The endpoint serves as a simple health check that requires authentication but performs no other operations.

Key changes:

• Added a new /ping endpoint to the OpenAPI specification that returns a "pong" message
• Updated API key documentation to include instructions for testing API keys using the new endpoint
• Added the "utility" tag group to organize health check and similar endpoints

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
reference/2024-02-05/openapi.json	Defines the new /ping endpoint under a "utility" tag, with a 200 response returning {"message": "pong"}
getting-started/api-key.mdx	Adds a "Testing your API key" section with curl example using the /ping endpoint and troubleshooting tips
docs.json	Adds the "Utility" group to the documentation navigation, referencing the ping endpoint page

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[hleimig]

Looks good to me

[dw-runa]

LGTM