Pass out the plan file from tf plan cmd AND pass it into the tf apply cmd

[jaskaransarkaria]

1/2 PRs

This PR outputs the plan file for the cloud-platform terraform plan command and takes a plan file to as an argument to be used in a cloud-platform terraform apply.

The next PR will push the plan file from the pipeline to our s3 bucket and respectively pulls the correct file from s3 to be used in terraform apply, these changes will be in our terraform-concourse repo here

• add flags to indicate whether we should output/ use a plan file
• output plan in the dir that the terraform plan is running from
• use plan file in terraform apply
• fix environments plan comment format