Switch template to Copier

See https://copier.readthedocs.io/en/stable/

This will allow to do the:

* search for "com_myorg_rules_mylang" and replace with the name you'll use for your workspace
* search for "myorg" and replace with GitHub org
* search for "mylang", "Mylang", "MYLANG" and replace with the language/tool your rules are for
* rename directory "mylang" similarly

steps for the user automatically after asking for those details.

Also, when this template involves, users can use Copier to pull in those changes to their instantiated projects. Ref: https://copier.readthedocs.io/en/stable/updating/

Start with the issue’s requested Copier workflow and read the linked Copier documentation, especially its updating guide. Identify the template content and substitutions described in the issue, then verify that a generated ruleset can be created and later updated through Copier.

Written by the indexing model from the issue text.