AzFilesHybrid - Add parametrized AD Credential for use with admin account or service account

In our business use cas, we have a seperated account for admin tasks. This admin account is highly securized : Strong password, MFA, and it can't open a session.

I am not able to use the module as released. So I forked it to add a "credential" parameter in cmdlet. Example :

```powershell
Join-AzStorageAccount `
-ResourceGroupName $ResourceGroupName `
-StorageAccountName $StorageAccountName `
-DomainAccountType $DomainAccountType `
-OrganizationalUnitDistinguishedName $OuDistinguishedName `
-Credential $credential
```
And I overloaded all `ActiveDirectory` module cmdlet call in `AzFilesHybrid`, with credential. In this way, I was able to use the module with my admin account.

Can you add this feature by design in your original module ?