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>

.github/workflows/linting.yml

@@ -36,6 +36,19 @@ jobs:
         with:
           terraform_version: 1.7.4
 
+      - uses: terraform-linters/setup-tflint@v4
+        name: Setup TFLint
+        with:
+          tflint_version: v0.50.3
+
+      - name: Init TFLint
+        run: |
+          cp .tflint.hcl ~
+          tflint --init
+        env:
+          # https://github.com/terraform-linters/tflint/blob/master/docs/user-guide/plugins.md#avoiding-rate-limiting
+          GITHUB_TOKEN: ${{ github.token }}
+
       - name: Install dependencies
         run: |
           pip install -r tools/requirements.txt
@@ -50,6 +63,9 @@ jobs:
         run: |
           terraform fmt -recursive -check -diff $GITHUB_WORKSPACE
 
+      - name: TFLint Modules
+        run: cd modules && tflint --recursive -f compact
+
       - name: Check documentation
         id: documentation-fabric
         run: |