[feature] support azure deployment stack whatif

**Background**
recently the azure deployment stack what-if feature was released GA
https://learn.microsoft.com/en-us/azure/azure-resource-manager/bicep/deployment-stacks-what-if?tabs=azure-cli

**Feature request**
Please support this newly created feature within this action.
Please also add an output for the action which contains information if there are changes or not. With this it would be possible to use the `create` operation conditionally to the output.