Resource for a managed image

[goncalo-rodrigues]

Cloud providers allow you to create a snapshot from a VM into a "managed image". You can't export them in general, so we can't support cross cloud.

AWS: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/ami_from_instance Azure: https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/image (vm needs to be "generalized")