Introduce Copier as a templating tool

In the #87 (closed) it was discovered that the cruft tool is not useful for updating the projects created from cookiecutter template. In turn, Copier-based POC prepared here https://gitlab.developers.cam.ac.uk/uis/devops/experiments/copier-webapp-du228/-/tree/main looks promising, upgrade wise. It can handle project upgrades based on git tags and populate new template with pre-stored answers.

Worth to try migrating this template to Copier.