move management of Vault back to tf_vault approle. for this, we need to
create a number of policies that are missing.
- add policies to manage consul secret engines
- add policies to manage pki secret engines
- add policies to manage kv secret engines
- add policies to manage ssh secret engines
- migrate from individual terraform files to config-driven terragrunt module structure
- add vault_cluster module with config discovery system
- replace individual .tf files with centralized config.hcl
- restructure auth and secret backends as configurable modules
- move auth roles and secret backends to yaml-based configuration
- convert policies from .hcl to .yaml format, add rules/auth definition
- add pre-commit hooks for yaml formatting and file cleanup
- add terragrunt cache to gitignore
- update makefile with terragrunt commands and format target
