Start-AzLogicApp Parameters not passed to Logic App workflow definition parameters

## Description

The 'Start-AzLogicApp' command has a 'Parameters' parameter that ['Specifies a parameters collection object of the logic app. Specify a hash table, Dictionary, or Dictionary'](https://docs.microsoft.com/en-us/powershell/module/az.logicapp/start-azlogicapp?view=azps-1.4.0). However, it seems the parameters are not passed into the Logic App.

## Steps to reproduce
Example script:
```powershell
$lAppParamObj = @{ 'paramRequestorFirstName' = "TestParameterPassedIn"}

Start-AzLogicApp `
-ResourceGroupName "test-rg" `
-Name "TestLogicApp" `
-Parameters $lAppParamObj `
-TriggerName "manual"
```

Logic App parameters definition
```json
"parameters": {
"$connections": {
"defaultValue": {},
"type": "Object"
},
"paramRequestorFirstName": {
"defaultValue": "test123",
"type": "string"
}
},
```

Initilising a variable within Logic App definition
```json
"Initialize_variable_2": {
"inputs": {
"variables": [
{
"name": "RequestorFirstName",
"type": "String",
"value": "@{parameters('paramRequestorFirstName')}"
}
]
},
"runAfter": {},
"type": "InitializeVariable"
},
```

The variable returns "test123" instead of "TestParameterPassedIn"