Add profiling and _internal stubs (#5686)

* Add profiling stubs

The purpose is to add enough data to generate the rest-api-spec.

* Add _internal endpoints

They are only here for the purpose of generating rest-api-spec files, so a lot
of the content is empty.

* Fix lint

* Update tsconfig.json

* Run make contrib

(cherry picked from commit 5f707db)

# Conflicts:
#	output/schema/validation-errors.json

Author: pquentin

compiler/src/steps/validate-model.ts

@@ -37,8 +37,6 @@ enum JsonEvent {
   array = 'array'
 }
 
-const privateNamespaces = ['_internal', 'profiling']
-
 /**
  * Validates the internal consistency of the model (doesn't check the json spec)
  *
@@ -220,11 +218,6 @@ export default async function validateModel (apiModel: model.Model, restSpec: Ma
   function validateEndpoint (endpoint: model.Endpoint): void {
     setRootContext(endpoint.name, 'request')
 
-    // Skip validation for internal endpoints
-    if (privateNamespaces.some(ns => endpoint.name.startsWith(ns))) {
-      return
-    }
-
     if (endpoint.request !== null) {
       const reqType = getTypeDef(endpoint.request)