Add credential support on PowerShell adapters

[Gijsreyn]

PR Summary

This PR addresses #328. It adds a like check for credentials and searches the username and password fields as input.

PR Context

PowerShell adapters currently don't support creating PSCredential objects. Most DSC community-based DSC resources have the $Credential as input. Some others may vary; that's why the -Like operator is used.

[michaeltlombardi]

This implementation seems to use the following snippet to determine whether to convert the input to a credential:

$_.Name -like '*Credential*' -and
$_.Value.Username -and
$_.Value.Password

However, I think we should probably consider checking the target property for whether it's expecting a credential or a secure string and then trigger handling.

[Gijsreyn]

If so, should we still check if the username/password is provided in such a way?

[Gijsreyn]

Just rewrote the part, but I'm struggling a little with the following error message from the pipeline:

Exception calling "Invoke" with "4" argument(s): "The 'ConvertTo-SecureString' command was found in the module
2025-04-21T14:56:29.911181Z TRACE dsc_lib::dscresources::command_resource: 890: PID 6992: 'Microsoft.PowerShell.Security', but the module could not be loaded. For more information, run 'Import-Module
2025-04-21T14:56:29.911238Z TRACE dsc_lib::dscresources::command_resource: 890: PID 6992: Microsoft.PowerShell.Security'."

The test I wrote earlier for Windows PowerShell seems to fail on this part. I have commented it out for now. I have seen this issue before with other modules that run under the agent and wasn't able to find a workaround for it. Any suggestions are welcome.

[Gijsreyn]

@SteveL-MSFT or @michaeltlombardi Do you perhaps have time to take another stab at this PR? The logic has changed to validate against the target property that is passed in.