[Feature]: New-AzCostManagementExport using unambiguous ISO 8601 dates

### Description of the new feature

Could you make it possible on the Cost Management reports to select the date format used in the CSV exports. Currently it uses the US centric format MM/DD/YYYY which is ambiguous? Ideally it should use the ISO 8601 YYYY-MM-DD format which is unambiguous and also allows for sorting of dates.

At a minimum providing a dateFormat configuration option where you could specify a date format (e.g. YYYY-MM-DD) or a common name (e.g. ISO8601)

For example:

New-AzCostManagementExport -DateFormat 'YYYY-MM-DD' ...

This above comment applies to everything in azure related to exporting of data, not just the cost management export.

### Proposed implementation details (optional)

_No response_