Allow using terratag as a validation tool

[Tomasz-Kluczkowski]

Is your feature request related to a problem? Please describe.
It is difficult to navigate developers and use company standard tags. At the same time we do not want any tool to be allowed to modify files. The tags required are very different for different resources and we cannot use any defaults.

Describe the solution you'd like
As a terratag user I want to be able to run it and report:

• which resources are without tags in which files
• and without any modifications done to the files
• and exit with code 1

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[TomerHeber]

Hi @Tomasz-Kluczkowski - great idea. I will review it.