Create independent formatting functions in terragrunt module to remove
dependency on terraform module. This significantly reduces dependencies
for users who only need terragrunt testing.

Changes:
- Add modules/terragrunt/format.go with formatting utilities
- Update init.go to use local formatting functions
- Remove terraform from terragrunt/go.mod dependencies
- Update workspace dependencies

Benefits:
- Users importing terragrunt no longer pull in HCL parsing libraries
- Reduced dependency bloat (no hashicorp/hcl, terraform-json, go-getter)
- Easier to update terragrunt independently from terraform

Create a shared formatting module to eliminate code duplication and
decouple terragrunt from terraform module dependencies.

Changes:
- Add modules/formatting module with HCL formatting utilities
- Update terraform module to use shared formatting functions
- Update terragrunt module to use shared formatting instead of terraform
- Remove duplicated format.go from terragrunt module
- Add comprehensive tests for formatting module
- Update go.work to include formatting module
- Update go.mod files with proper dependencies

Benefits:
- Terragrunt no longer depends on terraform module
- Eliminates code duplication (161 lines removed from terragrunt)
- Removes heavyweight dependencies from terragrunt:
  - hashicorp/hcl/v2
  - hashicorp/terraform-json
  - hashicorp/go-getter
  - tmccombs/hcl2json
  - zclconf/go-cty
- Maintains backward compatibility (all tests pass)
- Easier maintenance with single source of truth for formatting

Improve code clarity and maintainability:

Changes:
- Update comments in formatting module to reflect it's shared by both
  Terraform and Terragrunt (not Terraform-specific)
- Clarify comment in terragrunt/init.go about arguments being passed
  through to underlying terraform command
- Remove unnecessary replace directives from files/go.mod (logger and
  testing are not imported by this module)

All tests passing:
- formatting module tests: ✓
- terragrunt init tests: ✓
- builds successful: ✓

Fix CI build failure by reverting dependency upgrades that were
accidentally included in the modularization PR. This keeps the PR
focused solely on module structure changes.

Changes:
- Revert gruntwork-io/go-commons from v0.17.2 to v0.8.0
- Remove urfave/cli/v2 (keep v1.22.16)
- Downgrade dependencies in all module go.mod files
- Clean up indirect dependencies

The dependency upgrades introduced breaking API changes in
cmd/terratest_log_parser that should be addressed in a separate PR.

Fixes CI build errors in PR #1608