Update to use terraform_bin for state pull and help

This is a 🐞 bug fix.

[ ] 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)

I don't believe new tests are required since this only touches old code covered by existing tests.

Summary

Finds lingering hard references to terraform and replaces it with the found binary (which accommodates both terraform or tofu)

Context

This resolves #338 and #344.

How to Test

Any dummy terraspace project can be used to test - run against master with tofu and a project that uses -no-color and/or has outputs between stacks and do the same with terraform. Then try the same tests with my changes.

boltops-tools / terraspace