Generic support for cumulative updates has been added to speed up execution time of some scripts that were very long (in comparison with the vast majority of products), usually because they were involving a lot of HTTP requests.
This feature was developed particularily for the firefox.py and unity.py scripts, which was often very long to execute (a minute or moreaccording to GHA summaries). Those scripts has been updated to make use of this new feature.
This way the writing of the JSON file is handled automatically if the update does not fail.
It pave the way to further global improvements, such as a better error handling.
Up to now extra version fields were ignored: only name and date fields were accepted. This changes that by retaining the full JSON data when reading the file, making it possible in the future to support custom fields.
This also fixes a bug with versions having released on the same date: they was not ordered as expected (reverse order).
