Inventory terraform_state - add support for backend_config_files and update backend_config

[abikouo]

This pull requests add support for the parameter backend_config_files to provide Terraform configuration into files, this could be useful when the backend configuration contains some secrets.
To be aligned with the terraform init command, the backend configuration files should contain only key/values pair defining the configuration, here is an example of a s3 backend configuration

region = "us-east-1"
bucket = "tf-state-storage"
key = "terraform/tfstate"

However, as we are trying to read an existing Terraform state file from the provided backend, we need to generate a simple Terraform with the backend definition, this requires a new parameter backend_type
The generated configuration will look like

terraform {
   backend "<backend_type>" {}
}

We will also update the current backend_config parameter, which takes the full backend configuration by accepting only a dictionnary of key/values pairs to push as configuration to the backend when running terraform init --backend-config command.
Here is an example of an inventory file with the new modifications

inventory_state.yaml

plugin: cloud.terraform.terraform_state
backend_type: s3
backend_config:
   region: "us-east-1"
   key: "terraform/tfstate"
   bucket: "tf-state-storage"
backend_config_files: "aws_secrets.hcl"

With aws_secrets.hcl

access_key = "xxxxxxxxxxxxxxxxx"
secret_key = "xxxxxxxxxxxxxxxxx"

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[softwarefactory-project-zuul]

Build succeeded.
https://ansible.softwarefactory-project.io/zuul/buildset/f85615367c484e9688c31943994e1b76

✔️ ansible-galaxy-importer SUCCESS in 4m 33s
✔️ build-ansible-collection SUCCESS in 7m 23s

[softwarefactory-project-zuul]

Build succeeded.
https://ansible.softwarefactory-project.io/zuul/buildset/a2d0423219b04caaa745447ce8023daa

✔️ ansible-galaxy-importer SUCCESS in 3m 56s
✔️ build-ansible-collection SUCCESS in 7m 22s

[hakbailey]

A couple small comments but this looks good and works as expected!

[mandar242]

Tested changes to backend_config works as expected.

plugin: cloud.terraform.terraform_state
backend_type: s3
backend_config:
  region: us-west-1
  key: terraform/my.tfstate
  bucket: mandkulk-tf-test

ansible-inventory -i terraform_state.yaml --graph --vars
returns

@all:
  |--@ungrouped:
  |  |--aws_instance_example_server
  |  |  |--{ami = ami-0353faff0d421c70e}
  |  |  |--{arn = arn:aws:ec2:us-west-1:721012345678:instance/i-0bd1ca4a412345678}
  |  |  |--{associate_public_ip_address = False}
  |  |  |--{availability_zone = us-west-1a}
  |  |  |--{capacity_reservation_specification = [{'capacity_reservation_preference': 'open', 'capacity_reservation_target': []}]}
  |  |  |--{cpu_core_count = 1}
  |  |  |--{cpu_options = [{'amd_sev_snp': '', 'core_count': 1, 'threads_per_core': 1}]}
  |  |  |--{cpu_threads_per_core = 1}
...
...

[softwarefactory-project-zuul]

Build succeeded.
https://ansible.softwarefactory-project.io/zuul/buildset/3f9d8eb824cd43ee88b1ef5e36648f0d

✔️ ansible-galaxy-importer SUCCESS in 4m 17s
✔️ build-ansible-collection SUCCESS in 8m 07s

[softwarefactory-project-zuul]

Build succeeded.
https://ansible.softwarefactory-project.io/zuul/buildset/5283e69b84ba4788a4d76cc7b20f37b9

✔️ ansible-galaxy-importer SUCCESS in 4m 33s
✔️ build-ansible-collection SUCCESS in 7m 40s