tftest is incompatible with the terragrunt cli redesign

[mhulscher]

With the upcoming GA release of the terragrunt cli-redesign, tftest will fail to run terragrunt commands.

Most notably:

• run-all apply is being replaced with run --all -- apply
• -terragrunt-* params are replaced with newer variants

The old cli is still usable (although deprecated), while the new cli can already be used (or enforced with strict mode)