refactor(oas31): concentrate OpenAPI 3.1.0 code to separate plugin (#8475)

Refs #8474

test/e2e-cypress/static/documents/features/info-openAPI2.yaml

@@ -1,4 +1,5 @@
-swagger: 2.0.0
+swagger: "2.0"
+
 info:
   title: OpenAPI 2.0 Info Object
   version: 1.0.0

test/e2e-cypress/static/documents/features/license-openAPI2.yaml

@@ -1,4 +1,4 @@
-swagger: 2.0.0
+swagger: "2.0"
 info:
   title: OpenAPI 2.0 License with only url present
   version: 1.0.0

test/e2e-cypress/static/documents/features/license-openAPI31-identifier.yaml

@@ -5,5 +5,4 @@ info:
   description: This is a sample server for a pet store.
   license:
     name: Apache 2.0
-    # url: https://www.apache.org/licenses/LICENSE-2.0.html
-    identifier: Apache-2.0 # mutually exclusive of url; separately, for json_schema, consider const, prefix, array items can be of a different type (current assumption is all array items are the same)
+    identifier: Apache-2.0