PFX support for az ad sp create-for-rbac

[TheOnlyWei]

Related command
az ad sp create-for-rbac
https://learn.microsoft.com/en-us/cli/azure/ad/sp?view=azure-cli-latest#az-ad-sp-create-for-rbac

Is your feature request related to a problem? Please describe.
I want az ad sp create-for-rbac to support PFX certificate files.
az ad sp create-for-rbac just generates a PEM with --create-cert, which is difficult to convert to PFX in Windows PowerShell. It also doesn't accept an existing PFX file for --cert, forcing customers to have to convert their certificates to other certificates.

Describe the solution you'd like
az ad sp create-for-rbac should offer option to generate a PFX file or use an existing PFX file, since customers likely encrypt their certificates.

Describe alternatives you've considered
Only way is to install OpenSSL to convert PEM to PFX in Windows PowerShell. Would be much easier if az ad sp create-for-rbac supported PFX certificates since customers most likely want to encrypt their certificates anyway.

[yonzhan]

Thank you for opening this issue, we will look into it.