* fixed/ overhauld asset & blueprint scanning
* added polling for blueprints (not 100% sure yet)
* add-on-prefs => settings
* removed the now obsolete auto-export operator & preperences
* a lot of other minor changes
* 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
* 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
* added correct injection of assets + export path to blueprints
* moved a few common elements to "core" for better reuse
* more tweaks/ experiments with paths handling
* moved & overhauled a few of the blueprint & assets tools
* lots of minor tweaks & changes
