[Feature] - Update Gatekeeper policy to disable Finder contextual menu override

[cgryba]

The current Gatekeeper policy does not manage the Finder contextual menu override function.

The Mac Evaluation Utility presents a warning when this is not managed, per the following screenshot.

(More info is available at https://support.apple.com/en-ca/guide/deployment/dep61dc030/web.)

I've tested adding the requested domain and key (com.apple.systempolicy.managed and DisableOverride, respectively), and the warning goes away.

(Note for anyone reading this: if using Intune, you can find DisableOverride in a macOS configuration policy (Settings Catalog policy type), under System Policy Managed > Disable Override.)