feat: add support for exit code in terraspace validate command

[to-bar]

This is a 🙋‍♂️ feature or enhancement.

• [ ] I've added tests (if it's a bug, feature or enhancement)
• [ ] I've adjusted the documentation (if it's a feature or enhancement)
• [x ] The test suite passes (run bundle exec rspec to verify this)

Summary

terraform validate sets exit code 1 on failed validation, e.g.:

Error: Reference to undeclared input variable

$ echo $?
1

But terraspace not:

$ terraspace validate epi_cluster
=> terraform validate

│ Error: Reference to undeclared input variable

$ echo $?
0

Context

How to Test

1. Create a project
2. Break Terraform code, for example by making a typo in a variable name
3. Run terraspace validate <stack>
4. Run echo $? to check exit code
5. Add to config/app.rb:

   Terraspace.configure do |config|
   config.all.exit_on_fail.validate = true
   end

6. Run terraspace all validate
7. Run echo $? to check exit code

Version Changes