feat(openapi-tooling): custom validation server for test cases

Signed-off-by: aramissennyeydd <aramis.sennyey@doordash.com>

packages/backend-openapi-utils/package.json

@@ -33,15 +33,18 @@
     "test": "backstage-cli package test"
   },
   "dependencies": {
+    "@apidevtools/swagger-parser": "^10.1.0",
     "@backstage/backend-plugin-api": "workspace:^",
     "@backstage/errors": "workspace:^",
     "@types/express": "^4.17.6",
     "@types/express-serve-static-core": "^4.17.5",
+    "ajv": "^8.16.0",
     "express": "^4.17.1",
     "express-openapi-validator": "^5.0.4",
     "express-promise-router": "^4.1.0",
     "json-schema-to-ts": "^3.0.0",
     "lodash": "^4.17.21",
+    "mockttp": "^3.13.0",
     "openapi-merge": "^1.3.2",
     "openapi3-ts": "^3.1.2"
   },