feat(terraform): add custom build commands configuration (QOV-1351)

[fabienfleureau]

Add UI to configure custom Dockerfile commands for Terraform/OpenTofu services:

• File from repository option to reference a Dockerfile fragment file
• Inline commands option to provide commands directly
• "Show how it works" modal with usage examples

Summary

Issue: QOV-1351 Why As a user I want to execute any command in my terraform script by using local_exec operations. It means some binaries need be available during terraform execution. What Propose a way to install binaries at build time.

Screenshots / Recordings

Testing

• [x] Changes tested locally in the relevant Console's pages and Storybooks
• [x] yarn test or yarn test -u (if you need to regenerate snapshots)
• [x] yarn format
• [x] yarn lint

PR Checklist

• [x] I followed naming, styling, and TypeScript rules (see .cursor/rules)
• [x] I performed a self-review (diff inspected, dead code removed)
• [x] I titled the PR using Conventional Commits with a scope when possible (e.g. feat(service): add new Terraform service) - required for semantic-release
• [x] I only kept necessary comments, written in English (watch for useless AI comments)
• [x] I involved a designer to validate UI changes if I am not a designer
• [x] I covered new business logic with tests (unit)
• [x] I confirmed CI is green (Codecov red can be accepted)
• [x] I reviewed and executed locally any AI-assisted code