feat: Update mastering tutorial to use Infrastructure as Code

[ghislainbourgeois]

Description

This PR adds a Terraform module that deploys the required infrastructure to run the mastering tutorial. At the same time, it simplifies the setup by using LXD directly and using advanced features, like the automatic DNS on managed bridge networks.

The tutorial itself is simplified a lot and should be easier to run for users, with less chance for errors.

The Terraform module could also be reused for testing different scenarios.

Known issues:

• There is a race condition adding the SSH keys to the machines related to cloud-init execution. Retrying the terraform apply seems to work consistently.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that validate the behaviour of the software
• I validated that new and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have bumped the version of the library

[gatici]

Looks good. Great job.