Missing component diagnostics

[legrego]

Our HASSfest validation step is failing because we have certified as a gold or better integration, but we are missing diagnostics.

This is a new requirement that we should satisfy. Documentation on this appears sparse, so we may need to dig into HA's core code to understand how to use this.

From https://developers.home-assistant.io/docs/integration_quality_scale_index:

When communicating with a device or service, the integration implements the diagnostics platform which redacts sensitive information.

From our GH action:

Integrations: 1
Invalid integrations: 1

Integration elasticsearch - /github/workspace/custom_components/elasticsearch:
Error: R] [MANIFEST] gold integration does not implement diagnostics

[strawgate]

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