Change the template strategy: allow custom templates from packages

Proposal:

• don't copy the templates at the root of the fairified project
• copy only the necessary templates in the report folder during render:
  • use .template_dependencies file in the report folder and in the template folder to list necessary templates
  • syntax of the file is [package]:[template name] for example fairify:inrae
  • the .template_dependencies in the template folder ensures to process the dependencies in a recursion for copying the templates during render
  • use on.exit for deleting the templates after rendering
• change all paths ../../templates by templates