JSON creation keyword that adds the integer {{value}} to the current JSON List.

Example:

| `Start JSON Object`          |         |
| `Start JSON List`            | indices |
| `Add JSON List Integer Item` | 1       |
| `Add JSON List Integer Item` | 12      |
| `Add JSON List Integer Item` | 4       |
| `End JSON List`              |
| `End JSON Object`            |
| ${jsonString}=                 | `Create JSON String` |

{{jsonString}}:

| {
|    "indices": [1, 12, 4]
| }
