Print deprecation warning from Kuzzle

[Aschen]

Feature Description

Deprecation warnings can be added to the response to inform the developer when he is using a deprecated feature.

IMHO those warnings should be printed to the developer when he is developing his application:

• warnings should not be printed in production
• warnings printing should be configurable

⚠️ We need a small workshop first to discuss about this

See:

• https://docs.kuzzle.io/core/2/framework/classes/kuzzle-request/add-deprecation/#_Classes_KuzzleRequest_addDeprecation