Support terragrunt run-all executions

[yaronya]

Is your feature request related to a problem? Please describe.
Currently terratag supports terragrunt, but when running terragrunt using the run-all flag, not all files are getting digested by terratag.

Describe the solution you'd like
Terratag will successfully digest all files that would've been addressed by the terragrunt run-all flag.

Describe alternatives you've considered
One alternative, which isn't so viable, is to run terratag manually in a recursive manner for all folders addressed by the run-all command.

Additional context
N/A