Added "Scene Collection" menu to switch between different scene collections.

It works exactly like how the Profile menu works. I see this being useful for keeping the scenes list clean by having different scene collections for different things like a scene collection for Minecraft related scenes, or for experimenting with new scenes setup without messing up your old scenes setup. 

You can switch between different scene collections and add, rename, or remove scene collections while streaming.

All scene collections are stored in the "sceneCollection" folder.

When obs is updated for existing users their "scenes.xconfig" file will be moved to the "sceneCollection" folder.

Scene collections can be created/renamed/removed in "Settings:General".

Added "Profile: <ProfileName > SceneCollection: <SceneCollectionName>" to the beginning of the app name.