Add tflint to pipelines (#2220)

* Fix terraform_deprecated_index

https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.5.0/docs/rules/terraform_deprecated_index.md

* Fix terraform_deprecated_interpolation

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.5.0/docs/rules/terraform_deprecated_interpolation.md

* Fix more indexing

* Remove unused variable

* Enable TFLint for modules

* Add tflint config file

* Fix chdir

* Lint modules

* TFLint fixes

* TFLint

* Fixes binauthz README

* Fixes DNS response policy tests. Restores MIG outputs.

* Fixes other DNS response policy tests.

* Update tests for fast 2-e

* Moar fixed tests

---------

Co-authored-by: Simone Ruffilli <sruffilli@google.com>

modules/folder/main.tf

@@ -17,8 +17,8 @@
 locals {
   folder = (
     var.folder_create
-    ? try(google_folder.folder.0, null)
-    : try(data.google_folder.folder.0, null)
+    ? try(google_folder.folder[0], null)
+    : try(data.google_folder.folder[0], null)
   )
 }