[guardoni] Test scripts

[ascariandrea]

We now have a lot of fixtures for testing the parser that can be used also for testing guardoni.

By creating a .mjs script we can define a program that:

• accept a platform and nature parameters
• accepting an optional count to limit the fixtures loaded for the experiment
• load the fixtures from platforms/${platform}trex/backend/__tests__/fixtures/htmls/${nature} (and take only the first count if given)
• create an experiment with fixtures sources urls
• run the experiment
• verify fixtures expected metadata has been created properly by the parser

Running the script would be then something like ./cli-test-fixtures.mjs [yt | tk] [home | video | search | native | foryou | profile] ?[$number]

In this way we can easily test our infrastructure and automate data collection for development.