feat(audit): add authentication events

This patch adds two new events:
* auth_ok
* auth_fail, which may contain "verdict" describing user suspension.

Examples:

```json
{
  "id": "1.1.19",
  "message": "successfully authenticated user `guest`",
  "severity": "low",
  "time": "2023-11-30T19:02:10.708+0300",
  "title": "auth_ok",
  "user": "guest"
}
```

```json
{
  "id": "1.0.11",
  "message": "failed to authenticate user `borat`",
  "severity": "high",
  "time": "2023-11-30T18:58:48.635+0300",
  "title": "auth_failed",
  "user": "borat"
}
```