Invalid JSON when serializing an entity with alerts

[jpeletier]

While working on #1215 I noticed invalid JSON generated (duplicate field name) if requesting alerts when serializing an entity.

Describe the bug

A repeated JSON field alerts appears when serializing an entity that has alerts, the first time to indicate there are alerts, the second time to provide an array of alerts:

{
 "name": "e1",
 "alerts": true, // <--- repeated field name
 "components": {
   "flecs.alerts.AlertsActive": {
     "info_count": 0,
     "warning_count": 0,
     "error_count": 2
   },
   "Position": null
 },
 "alerts": [ // <--- repeated field name
   {
     "alert": "position_without_mass.e1_alert_2",
     "message": "e1 has Position but not Mass",
     "severity": "Error"
   },
   {
     "alert": "position_without_velocity.e1_alert_1",
     "message": "e1 has Position but not Velocity",
     "severity": "Error"
   }
 ]
}

To Reproduce
Steps to reproduce the behavior:

See test SerializeEntityToJson_serialize_w_2_alerts in test/meta/src/SerializeEntityToJson.c

Expected behavior

the "alerts": true field perhaps should be renamed to "hasAlerts": true to avoid name collision.

Additional context
Add any other context about the problem here (operating system, hardware, ...).

[SanderMertens]

Fixed!