Trigger payload comparision fails when parameter value is `[]`

When comparing triggers with the PrePostDeploymentScript.Ver2.ps1, the script fails to compare triggers where there are payload parameters with an empty array as value.

Sample trigger configuration:

```json
{
"name": "schedule_daily_datasource",
"properties": {
"annotations": [],
"runtimeState": "Started",
"pipelines": [
{
"pipelineReference": {
"referenceName": "0_orchestrate_dataSource_full",
"type": "PipelineReference"
},
"parameters": {
"thresholdNumberOfRows": 100000,
"fullDataTablesConfig": []
}
}
],
"type": "ScheduleTrigger",
"typeProperties": {
"recurrence": {
"frequency": "Day",
"interval": 1,
"startTime": "2022-09-21T09:32:00Z",
"timeZone": "UTC",
"schedule": {
"minutes": [
30
],
"hours": [
4
]
}
}
}
}
}
```

The script then fails with the following error:

```
Comparing 'schedule_daily_datasource' trigger payload
##[warning] Unable to compare 'schedule_daily_datasource' trigger payload, this is not a failure. You can post the issue to https://github.com/Azure/Azure-DataFactory/issues to check if this is user error or limitation.
##[warning] Cannot bind argument to parameter 'ReferenceObject' because it is null. from Line: 428
```

The issue is that the empty array evaluates to `$null` in Line 428 and Compare-Object does not accept null values.

See example:
```powershell
("[]" | ConvertFrom-Json) -eq $null
True
```