fix: allow game to quit without waiting for registry updater thread

[keturn]

This fixes #3940. The thread that was holding things up there was this one that's updating the mod registry.

How to test

• Start Terasology. Push the Exit Terasology button quickly, before everything has time to settle.
• Make sure the window not only closed, but the process has quit as well. i.e. you see "process finished with exit code 0" in intellij or "build successful" and a return to the command line from the gradle task.

Outstanding before merging

• use a more convenient and readable thread runner

[keturn]

The initial version of this I've provided here is deliberately verbose.

Not that I want creating threads to be easy, but I certainly don't want the right way to be this much more difficult than the wrong way.

The three qualities we've got here are:

1. takes a Callable, returns a Future
2. is a daemon thread
3. has a name that tells us something useful about what it's doing or where it was spawned

and I threw in the abbreviator for good measure, but

org.terasology.rendering.nui.layers.mainMenu.advancedGameSetupScreen.AdvancedGameSetupScreen#initialise

is a really long string.

[keturn]

Side note: Is it surprising that this is running as soon as the MainMenuScreen is initialized? The user may never visit the AdvancedGameSetupScreen.

[keturn]

oh, that distracted me from what I was saying about my deliberately-verbose implementation. That's a straw man, posted here in the hope of generating discussion that will point toward an existing utility, or some agreement about where to add this as a new utility function.

[DarkWeird]

"ModuleRegistryUpdater" sounds better and more ralate then "AdvancedGameSetupScreen"

[pollend]

Just tested this with and without the PR and the game exits correctly when closing.