Auto discovery of the state file from terraform backend block

[sjourdan]

Description

As suggested by @Gary-Armstrong, to be able to specify a --from tfstate is good enough, but by reading the right terraform file we could get the same information and build the option automatically for the user:

terraform {
  backend "s3" {
    bucket = "the-bucket-name"
    key    = "some-directory-name"
    region = "us-east-1"
    dynamodb_table = "some-statelock"
  }
}

Sidenote: it should also work dynamically for people with different workspaces.

⚠️ this feature breaks the initial assumption that driftctl runs without any need to access the TF HCL code. ⚠️ this feature may make the multi-state feature less obvious

Example

[eliecharra]

We should dig into this and think about it with terraform code as a potential IaC source in mind. This is something potentially bigger than it looks

[troxil]

Consider also the same configurations can be given via terraform Environment variables too. Which is how I mainly use terraform (backend bucket config is an env var)

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[sundowndev]

This was done in #1555