Update configuration management cmdlets

- Added Get-OPNSenseConfig cmdlet that retrieves the OPNSense configuration as an XML document
- Updated Restore-OPNSenseConfig to accept an XML document from the pipeline or as a parameter
- Changed Export-OPNSenseConfig and Import-OPNSenseConfig to use System.IO.FileInfo for the Path parameter
- Removed Backup-OPNSenseConfig cmdlet (use Get-OPNSenseConfig instead)
- Updated documentation and examples

docs/cmdlets/Get-OPNSenseConfig.md

@@ -0,0 +1,52 @@
+# Get-OPNSenseConfig
+
+## SYNOPSIS
+Gets the OPNSense firewall configuration as an XML document.
+
+## SYNTAX
+
+```
+Get-OPNSenseConfig
+```
+
+## DESCRIPTION
+The Get-OPNSenseConfig cmdlet retrieves the OPNSense firewall configuration and returns it as an XML document.
+
+## EXAMPLES
+
+### Example 1: Get the configuration as an XML document
+```powershell
+$config = Get-OPNSenseConfig
+```
+
+This example retrieves the OPNSense firewall configuration as an XML document.
+
+### Example 2: Get the configuration and pipe it to Restore-OPNSenseConfig
+```powershell
+Get-OPNSenseConfig | Restore-OPNSenseConfig
+```
+
+This example retrieves the OPNSense firewall configuration and restores it.
+
+## PARAMETERS
+
+### CommonParameters
+This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutVariable, -OutBuffer, -PipelineVariable, -Verbose, -WarningAction, and -WarningVariable. For more information, see [about_CommonParameters](http://go.microsoft.com/fwlink/?LinkID=113216).
+
+## INPUTS
+
+### None
+
+## OUTPUTS
+
+### System.Xml.XmlDocument
+The OPNSense configuration as an XML document.
+
+## NOTES
+This cmdlet requires a connection to an OPNSense firewall. Use Connect-OPNSense to establish a connection.
+
+## RELATED LINKS
+
+[Restore-OPNSenseConfig](Restore-OPNSenseConfig.md)
+[Export-OPNSenseConfig](Export-OPNSenseConfig.md)
+[Import-OPNSenseConfig](Import-OPNSenseConfig.md)