[Feature]: New-AzSqlDatabaseExport auth with Access Token

### Description of the new feature

Currently the New-AzSqlDatabaseExport cmdlet only allows access through Sql credentials or ADPassword. Proposing the option to authenticate through an Access Token generated with the Get-AzAccessToken cmdlet. This other form of authentication would allow for secure access to the SQL DB Export functionality without having to hand over SQL admin credentials or specific user AD credentials.

This same functionality is being proposed in azure cli [20645](https://github.com/Azure/azure-cli/issues/20645).

Something similar can be seen in SqlPackage Export with the /AccessToken [parameter](https://docs.microsoft.com/en-us/sql/tools/sqlpackage/sqlpackage-export?view=sql-server-ver15#parameters-for-the-export-action). Which would be a great option but is not currently available in the Azure Powershell Runbook 5.1 (from what I've seen).

### Proposed implementation details (optional)

_No response_

Start at the New-AzSqlDatabaseExport cmdlet and compare its current SQL credential and ADPassword authentication options with the Get-AzAccessToken and SqlPackage /AccessToken references linked in the issue. Determine the existing export authentication entry points and tests, then add access-token support while preserving the current methods; done means an access token can authenticate the export successfully.

Written by the indexing model from the issue text.