opentofu/terraform resources for secure bootable images on GCP

[yeoldegrove]

What would you like to be added:

We need changes to the upstream terraform provider for GCP to enable secure bootable images that let us bring our own secure boot config and keys.

Why is this needed:

I identified potential blockers to go forward with the openTofu implementation of our secure boot use cases.

• shielded_instance_initial_state needs to be passed to the image
• shieldedInstanceInitialState
• Terraform google compute_image resource

The terrafom google_compute_image resource cannot define shielded_instance_initial_state at the moment.

• This could potentially be implemented (assessment needed).
• This could be potentially be worked around by patching the image later (assessment needed).

Upstream Issue opened here: https://github.com/hashicorp/terraform-provider-google/issues/20303

[NotTheEvilOne]

Support has been prepared in https://github.com/b1-systems/google-magic-modules/tree/prs/add-support-for-shieldedInstanceInitialState