Add google_disabled_api rule

[wata727]

Fixes #2

This PR enables deep checking for the Google provider. As a feature of the deep checking, I will add the google_disabled_api rule that finds resources that depend on APIs that have not been enabled using the Service Usage API.

$ tflint
1 issue(s) found:

Error: Compute Engine API has not been used in [project_id] before or it is disabled. (google_disabled_api)

  on template.tf line 25:
  25: resource "google_compute_network" "vpc_network" {

The correspondence between Terraform resources and API uses the products file generated from the Magic Module. See also terraform-linters/magic-modules#1

To enable this rule, change the plugin definition to enable deep checking as follows:

plugin "google" {
  enabled = true
  deep_check = true
}

I'm using the Service Usage API to get API status, but I'm wondering if this is the best option. In order to take advantage of this rule, you need to enable the Service Usage API, so it might be better to implement a rule for each resource and call an API in each rule.

TODO

• Describe limitations of credentials in deep checking
• Cache API response
• Add tests