:sparkles: [ENH] Have a isAsynchronous property on a realm

Sugoi can read and write on different stores that are replicated after a lapse.
We should have a property on the realm (maybe isAsynchronous ?) that will identify a realm as writing and reading on different stores.
This property then could be used to return a dedicated exception on synchronous only request or to determine if the existence of an id can be checked (see sugoi-api-core\src\main\java\fr\insee\sugoi\core\service\impl\UserServiceImpl.java#84)