Support input for auto definting the HTTP backend

.gitlab/README.md.template

README.md

src/gitlab-tofu.sh

templates/apply.yml

templates/destroy.yml

templates/full-pipeline.yml

templates/graph.yml

templates/job-templates.yml

templates/plan.yml

templates/test.yml

templates/validate-plan-apply.yml

templates/validate-plan-destroy.yml

templates/validate-plan.yml

templates/validate.yml

tests/iac-auto-define-backend/main.tf

tests/iac-auto-define-backend/tests/main.tftest.hcl

tests/integration-tests/AutoDefineBackend.gitlab-ci.yml

tests/integration.gitlab-ci.yml