fix: Correctly get inventory objects registered in other rooms

[MatteoPiovanelli]

This fixes godot-escoria/escoria-issues#280

As I mentioned on Discord, when an object is added to the inventory it is added to an array for the room the player is currently in. When get_object got called, it would only look in the current room, skipping all possible inventory items from other rooms.

This fix gets around that, specifically for items that are registered in the inventory.

I'm opening this as a draft because I'm not 100% this is the entirely correct solution. (and on top of that, I'm not 100% I followed the contribution guidelines correctly)
A better approach could be to have a separate array for inventory items. I noticed it's not there, and I don't know the history of the reasoning why.
Alternatively, yet another approach could be to have a similar loop through the objects in the rooms, but to wrap that in a func in the inventory manager, to "hide" its implementation details from the object manager.

[StraToN]

I'll test the branch before reviewing. Sorry for the delay

[StraToN]

Ok, the fix does fix the issue great, thanks a lot!

I am not exactly certain why we didn't do that already: maybe I wanted to have all inventory items to be automatically registered at each room change, so that they are accessible through object_manager.room_objects array anytime? Anyway, the right way was to use object_manager.get_object() method so this fix is ok to me.

Approved. Thanks a lot!

[StraToN]

Thanks !