Show a preview of the resources that will be provisioned in the CLI

[raksiv]

Allowing people see the resources that will be provisioned before they are provisioned builds confidence that it isn't just 'magic'

We may also want the option of spitting out the OpenAPI spec / Policies documentation as a command

This only applies for the Pulumi providers, the Terraform providers already have a preview function in the form of plan and apply.

[davemooreuws]

The OpenAPI Spec can be downloaded already but it is in a three dot menu.

Would this be based on the stacks in the project?