New model for test tagging

[rodgco]

To simplify defining which test to run, I've implemented this change that will tag the default test structure, and tests can be run with the following commands:

$ mix test --only y2024
$ mix test --only y2024.d01
$ mix test --only y2024.d01.p1

It is easier than editing tests and removing :skip tags.

Test tags follows the same structure of the tasks to effectively run your code against your input. So it is easier to change from one to another.