Technichal improvement: New romfs v2

Thank you for your contribution!

Please make sure your Merge Request is ready to be merged:

• a line describing your modifications has been added to CHANGELOG.md
• a line describing tests to make before release has been added to TESTING.md
• if the Merge Request is about a new feature, an improvement or an important bugfix, amend RELEASE-NOTES.md
• you respected conventional commits

The results of the build can give you clues about what is missing in your Merge Request.

Changes :

• New ROMFS implementation in Python 3.8+
• New es_systems.xml format
• New metadata in systems & emulators
• Faster to build

Thanks to @Akkeoss & @Pitch64 for the help filling in all the new system descriptors :)

Related to #1686 (closed)