Added functionality to write tfvars files

[arueth]

Trying to simplify and codify the configuration of the platform.

[ferrarimarco]

A couple of questions.

• Do we need to update READMEs when instructing users about how to provide variable values?
• The FL use case scripts adding some values to these config files (ref). Do you also need to refactor that?

[arueth]

A couple of questions.

• Do we need to update READMEs when instructing users about how to provide variable values?
• The FL use case scripts adding some values to these config files (ref). Do you also need to refactor that?

So the goal of this is that you can either set all your variables in the tfvars files or you could set them with the TF_VARS environment variables. Once you run initialize all of the configured values would be written to the tfvars files and they become the source of truth, can be version controlled, etc.

I was running into some issues going into the individual Terraservices and trying to run them manually because some of the values were set in various places. This should make it so you can go into any Terraservice and run it manually.

It shouldn't need to be refactored because it will read the values from the tfvars files. We might consider creating a common script for updating configuration values in the tfvars files.

[arueth]

Ideally this same logic would be applied to the _shared_config folders for each use-case as well I just wanted to prototype it for the base/core configuration.