Breaking changes to Get-AzAccessToken

**Is your feature request related to a problem? Please describe.**
No. The Get-AzAccessToken module has some breaking changes incoming. The token property will go from string to securestring.

**Describe the solution you'd like**
Maybe updating both the fetchAddressPrefix.bicep and fetchAddressPrefix.ps1 in _examples/azure-eslz/_ to reflect this change.
We have updated it from > to:
From: $accessToken = ConvertTo-SecureString (Get-AzAccessToken -ResourceUrl $Env:IPAM_API_SCOPE).Token -AsPlainText
To: $accessToken = (Get-AzAccessToken -ResourceUrl $Env:IPAM_API_SCOPE -AsSecureString).Token

**Describe alternatives you've considered**
None.

**Additional context**
Add any other context or screenshots about the feature request here.