Chore: tool config and workflow updates

[bcdady]

This pull request introduces several foundational improvements to the repository's infrastructure, focusing on code consistency, automated dependency and Terraform checks, and security/static analysis. The most important changes are grouped below:

CI/CD and Automation Enhancements:

• Added a GitHub Actions workflow for Terraform CI, automating formatting, initialization, validation, linting (TFLint), and security scanning (TFSec and Checkov) for all pushes and pull requests to main (.github/workflows/terraform.yml).
• Introduced a Dependency Review workflow using GitHub Actions to automatically review dependencies on pull requests (.github/workflows/dependency-review.yml).

Dependency Management Improvements:

• Updated Dependabot configuration to:
  • Set reviewer(s) for PRs,
  • Limit open PRs,
  • Add support for github-actions ecosystem in addition to Terraform (.github/dependabot.yml).

Code Quality and Consistency:

• Added an .editorconfig file to enforce consistent code style across the project, including indentation, line endings, and file-specific overrides (.editorconfig).

Static Analysis and Linting:

• Added a TFLint configuration file to enable recommended rules and enforce Terraform best practices, including naming conventions and documentation requirements (.tflint.hcl).
• Added a TFSec configuration file to exclude a specific Cloudflare DNS record rule from security scanning (.tfsec.yml).