[AI] StateTree assets need to be compiled again when restarting the editor despite no changes.

StateTree assets show that there are pending changes to compile when reloading the editor. This can also mean that state trees do not run logic for AI as noted in linked UDN thread.

1. Save and compile a StateTree asset
2. Close editor
3. Re-open editor and open StateTree asset

Expected Result: The StateTree asset is up-to-date and the compile button shows a green checkmark.

Actual Result: The StateTree asset does not appear up-to-date and the compile button shows pending changes with a yellow question mark.