api: Convert the API specification to OpenAPI 3.2

Move reusable schemas into components and describe request bodies and
response media types using OpenAPI 3.2 with the OpenAPI 3.1 schema
dialect. Preserve schema property order, reference annotations,
examples, custom formats, and Go generator extensions.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

api/docs/CHANGELOG.md

@@ -15,6 +15,9 @@ keywords: "API, Docker, rcli, REST, documentation"
 
 ## v1.57 API changes
 
+* The API specification now uses OpenAPI 3.2.0 instead of Swagger 2.0.
+  A generated Swagger 2.0 version is still available for existing tooling.
+
 ## v1.56 API changes
 
 * `GET /containers/json` now supports an `annotation` filter to filter