[RPD-312] Update base_template/azure_template files to handle new modular Terraform files

[Christopher-Norman]

This PR adds the functionality for using the modular implementation of Matcha. It mainly updates the copy_file function within AzureTemplate class to recursively copy and concatenate Terraform files from the modules to the target destination.

This allows users to add modules to their stack to make a custom stack and provision only the required modules.

{"stack": {"name": "custom", "experiment_tracker": "mlflow", "orchestrator": "zenml", "deployer": "seldon", "vector_database": "chroma"}}

Checklist

Please ensure you have done the following:

• [x] I have read the CONTRIBUTING guide.
• [x] I have updated the documentation if required.
• [x] I have added tests which cover my changes.

Type of change

Tick all those that apply:

• [ ] Bug Fix (non-breaking change, fixing an issue)
• [x] New feature (non-breaking change to add functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Other (add details above)