* coherence pass : "main" scenes & co renamed to "level" scenes & co
* auto export now toggled ON by default, but bailing out early if there are no main & lib scenes added
* UI improvement for adding level/lib scenes
* minor cleanups
* removed a lot of obsolete code
* overhauled settings upsert
* added save & load of blenvy common settings
* removed most of the specific uis (mostly auto export)
* moved change detection logic out of auto export (wip)
* added helper to compare setting dicts
* cleaned up some incoherent naming
* stripped auto_export of a lot of its internals (wip)
* main settings ui overhaul: now components & auto export provide their own settings UI function
* 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
