[WIP] Add QUndoStack undo/redo to SmartProp Editor#13

Copilot wants to merge 1 commit intomaindertwist/Hammer5Tools:mainfrom

copilot/add-qundo-support-to-smartpropdertwist/Hammer5Tools:copilot/add-qundo-support-to-smartpropCopy head branch name to clipboard