Lua: Add more built-in event handlers

A lot of our API, such as Lockable.lock, can only be called or modified from global scripts, or from a local script attached to the target. This typically requires modders make scripts whose sole purpose is to add an event handler to call these API functions. It would be better if we provided built in set of event handlers to address remote calls, so modders do not have to re-invent them every time.

!4738 (merged) adds some such event handlers (the ones relevant for !3029 )