Manage time singleton in register_core_types

[rune-scape]

the time singleton is used rlly early on, and Time::get_singleton() was always called before it was initialized, creating a memory leak when it memnewed, then ObjectDB caught the stray instance
this registers it in a more specific place right after StringName and ObjectDB are initialized,

[aaronfranke]

Makes sense to me, we want to unify where this is created and have it be as early as possible.

[aaronfranke]

If it runs it should be good.

[akien-mga]

Thanks!