[Entity Analytics] Add Asset Criticality public API docs

[hop-dev]

Asset criticality API docs.

https://security-docs_bk_5660.docs-preview.app.elstc.co/guide/en/security/master/asset-criticality-api-overview.html

Open questions:

• should I add a link from the asset criticality page at /security/master/asset-criticality.html to these API docs?
• All APIs require the elastic-api-version: 2023-10-31 header, I dont see the other API docs talking about API versioning?
• How to format arrays of objects in the request body e.g https://github.com/elastic/security-docs/pull/5660/files#r1704133538

[github-actions]

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[mergify]

This pull request does not have a backport label. Could you fix it @hop-dev? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• v7.x is the label to automatically backport to the 7.x branch.
• v7./d./d is the label to automatically backport to the 7./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.