Add a "kube_config_file_path" to aks module output

[howlowck]

As a:
... Environment Creator

I want:
... To seamlessly use Helm or Kubernetes Terraform Provider with Bedrock

So that:
... the Environment infrastructure can be completely managed by Terraform

Describe the solution you'd like:
Add the file path of the local_file.cluster_credentials resource for the aks module.

Acceptance Criteria:

provider "helm" {
    kubernetes {
        config_path = module.bedrock_aks.kube_config_file_path
    }
}

Describe alternatives you've considered:

We are currently using the aks data source to get the information from the cluster. It's a less elegant solution because we have to explicitly declare the dependency.

Additional context:

• Helm Provider Doc

Does this require updates to documentation?:
No

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I plan to make a PR to implement this feature, if the community thinks this is a good idea.