Bad examples for `Invoke-AzCostManagementQuery`

### Type of issue

Code doesn't work

### Feedback

People would use `Invoke-AzCostManagementQuery` to retrieve cost information, but the listed examples do not return any actual cost data. This is due to the way the underlying API is designed: if you don't request any `aggregation`s, then you just get empty response rows.

For contrast, here's an API request as sent by the Azure Portal. Notice the `aggregation` property.

```
POST https://management.azure.com/subscriptions/00000000-0000-0000-0000-000000000000/providers/Microsoft.CostManagement/query?api-version=2021-10-01&$top=5000
```
```json
{
"type": "ActualCost",
"dataSet": {
"granularity": "None",
"aggregation": {
"totalCost": {
"name": "Cost",
"function": "Sum"
},
"totalCostUSD": {
"name": "CostUSD",
"function": "Sum"
}
},
"grouping": [
{
"type": "Dimension",
"name": "ResourceGroupName"
},
{
"type": "Dimension",
"name": "ChargeType"
},
{
"type": "Dimension",
"name": "PublisherType"
}
]
},
"timeframe": "Custom",
"timePeriod": {
"from": "2024-09-01T00:00:00+00:00",
"to": "2024-09-30T23:59:59+00:00"
}
}
```

Mimicking that API call, here's an example for `Invoke-AzCostManagementQuery` that _does_ return cost data:

```
Invoke-AzCostManagementQuery -Scope /subscriptions/00000000-0000-0000-0000-000000000000 -Timeframe MonthToDate -Type ActualCost -DatasetGranularity 'Monthly' -DatasetAggregation @{ 'totalCost' = @{ 'name' = 'Cost' } }
```

```
Column Row
------ ---
{Cost, BillingMonth, Currency} {1.54425705929919 01 Sept 2024 00:00:00 EUR}
```

Could you update the docs to list more helpful examples?

Related: #20749

### Page URL

https://learn.microsoft.com/en-us/powershell/module/az.costmanagement/invoke-azcostmanagementquery?view=azps-12.3.0&viewFallbackFrom=azps-10.4.1

### Content source URL

https://github.com/Azure/azure-powershell/blob/main/src/CostManagement/CostManagement/help/Invoke-AzCostManagementQuery.md

### Author

@mikefrobbins

### Document Id

3dff2f6a-7cc0-e478-2079-8a417fc895dd

Read src/CostManagement/CostManagement/help/Invoke-AzCostManagementQuery.md and compare its current examples with the API request and working command shown in this issue. Update the examples so they request aggregations and return cost data, then verify the documented commands and output against the related guidance in issue #20749.

Written by the indexing model from the issue text.