Support Terraform workspaces for creating infra on demand

[dsalaza4]

We can use Terraform workspaces to provision multiple replicas of the same infrastructure. This can be very useful when dealing with development environments.

Let's make Terraform builtins support passing an environment variable name that can be later evaluated to use a specific Terraform workspace.

That way it would be possible to use custom Makes jobs for selecting a workspace and then passing it via environment to such builtins.

Make the following builtins support a workspace environment variable:

• testTerraform
• deployTerraform
• taintTerraform

[dsalaza4]

I think creating a workspaceForTerraformFromEnv builtin that could later be imported by the setup would be much better.