refactor(analytics): tests, error handling and authentication

Différences :

diff before.txt after.txt
2c2
< Headers: __TypeId__: fr.gouv.tac.analytics.server.model.kafka.Analytics
---
> Headers: empty

Suppression du header TypeId.

Ancien format de message publié dans kafka :

Key: empty
Timestamp: 2021-06-23 09:43:59.862
Headers: __TypeId__: fr.gouv.tac.analytics.server.model.kafka.Analytics

{
   "installationUuid":"BBBBBB-21546-cd254212-7e5454df",
   "infos":null,
   "events":[
      {
         "name":"event2",
         "timestamp":"2021-05-28T11:42:11.122Z",
         "desc":"my event BBBB"
      }
   ],
   "errors":null,
   "creationDate":"2021-06-23T11:43:59.693564+02:00"
}

Message apres refactoring :

Key: empty
Timestamp: 2021-06-22 09:33:41.482
Headers: empty

{
   "installationUuid":"BBBBBB-21546-cd254212-7e5454df",
   "infos":null,
   "events":[
      {
         "name":"event2",
         "timestamp":"2021-05-28T11:42:11.122Z",
         "desc":"my event BBBB"
      }
   ],
   "errors":null,
   "creationDate":"2021-06-23T11:43:59.693564+02:00"
}