Wrapper around terraform plan
gen3 tfplan [--destroy]:
Run 'terraform plan' in the current workspace, and generate plan.output.
A typical command line (under the hood) is:
terraform plan --var-file ./config.tfvars -var-file ../../aws.tfvars -out plan.terraform ~/Code/PlanX/cloud-automation/tf_files/aws/commons 2>&1 | tee plan.log
If '--destroy' is passed, then a destroy plan is generated.
Execute a generated plan with 'gen3 tfapply'