Implementing OpenApi 3 specs (converted from Swagger 2) (#53243)

* Adding OpenApi target to makefile, to covert swagger spec into OpenAPI 3
* Adding endpoint to server swaggerui with new openapi3 specs
* Passing output file as parameter for OpenApi3 specs
* Implement workaround for missing host and prefix domain

pkg/api/api.go

@@ -187,6 +187,7 @@ func (hs *HTTPServer) registerRoutes() {
 
 	if hs.Features.IsEnabled(featuremgmt.FlagSwaggerUi) {
 		r.Get("/swagger-ui", swaggerUI)
+		r.Get("/openapi3", openapi3)
 	}
 
 	// authed api