* fixes & experiment to auto export
* added support for "always export" functionality for blueprints & levels
* fixed issues with asset management
* fixed issues with tracker
* more ui improvements (display of the number of assets etc)
* a lot more minor tweaks
* added Asset propertygroup & User Assets collections to collections & scenes to store them explicitely
* overhauled UI to make use of this : also means names & paths are editable after the fact
* overhauled testing asset hierarchy scan accordingly
* added expertimental export of bevy_asset_loader compatible asset.ron files per level
* related tweaks & additions
* minor tweaks & improvements to assets handling
* renamed a few auto export preferences for more coherence
* "assets" folder is now mandatory again and used by the various sub asset types
* blueprints/levels/materials paths in auto_export are not overwrite their relative values anymore,
but added their "full" variants & changed code using full paths to use those
* added back gltf exporter post export callback, in a cleaner fashion
* changing (wip) the way the various relative folders are auto generated in the folder selection UI
* lots of other minor tweaks & improvements
* improvements to assets ui
* assets ui now specific to per level data, not based on selection anymore
* blueprints ui now presents assets per blueprint
* a lot of tweaks & improvements in the areas above