Add copy/paste and duplicate for game objects

[ambrosiogabe]

We should have copy paste working. If there's an active object selected and an active timeline clip selected:

• If the user is hovering over the editor viewport OR the scene hierarchy panel, copy/paste the selected game object

When pasting a game object, add the object to the scene at the same position as the copied object. The new object should automatically be selected as the new active object so any changes now happen to the copied object.

Copy/paste menus should also be available. Right-clicking an object in the viewport, the object in the scene hierarchy panel.

When pasting from a menu:

• If you click the object in the scene hierarchy panel and click paste, it should paste the content as a child of the game object clicked.
• When right-clicking an empty area in the scene hierarchy panel, the pasted game object should be pasted at the bottom of the panel.