Unity 6 support and other improvements

What's Changed

Added

• Added new context menu to move items between collections
• Added new Rename context menu
• Added new CollectionItemQuery to be used with ItemPIcker

Changed

• Improved Unity 6 support
• Fixed null ref when collections settings where not set
• Fixed some renaming issues
• Changed event where non automatically loaded items are removed on editor simulation
• Fixed null ref on empty collection

• Ensured that the namespace for generated code is the same as the script by default by @RoyTheunissen in #161
• Feature/unity 6 support by @brunomikoski in #162

Full Changelog: v2.3.6...v2.3.7