Allow external custom object types #3494

Is your feature request related to a problem? Please describe. 1.9+ rework of object types migrated the property type information to the project file, rendering objecttypes.xml obsolete and unreliable. That created 2 problems: Now to obtain information about object types user have to either bundle the project file alongside the game assets (which is undesirable) or to manually re-export the object types every time a change occurs (which can be quite a lot during development). And objecttypes.xml does not list the defined enum types, which are only available in json form now.

Describe the solution you'd like Add an option to specify an external source for object types or at the very least an auto-export function so that it can be always kept up to date. Ability to specify external source also adds a benefit of making it easier for external tools to auto-generate types as they have no chance of messing up the project file other fields as well as make it semi-backwards-compatible with old objecttypes.xml in a way they worked.

Describe alternatives you've considered

• Manual re-export of the object types on every change. This may sound like an okay solution for a while, but when you actively develop the game and add new/modify types frequently - it becomes tedious extremely fast.
• Bundle the project file alongside game assets. This is undesirable as project files can contain information you may not want to bundle. Such as absolute paths.