Scripting: Property Changed Event

I hope when user changed the object's property value, the script could get a signal, then do something.

The issue names no files, tests, or entry points. Start by locating the scripting integration and the code that changes object properties, then determine how a property-change signal should be exposed to scripts. Done means the requested event behavior is defined and verified, but the issue does not specify its API or expected tests.

Written by the indexing model from the issue text.