Stopwatch API

[Privatech38]

This PR adds API for stopwatches added in 1.21.11.

What worries me is that restart replaces the handle only for the instance it was called on and not other instances that reference the same handle.

[lynxplay]

Not trying to sound rude but, what would event be a usecase for this addition.
The only remote thing I could maybe ever think of is some weird plugin<->datapack interaction but that seems very very far fetched.

Any plugin can already use google commons or apaches StopWatch to achieve the same.
This, at least right now to me, feels like exposing something just for the same of exposing it.

[Privatech38]

From what I gathered it saves on server shutdown which does help in some niche cases I suppose.

I do agree there aren't many use cases and wouldn't mind if the PR is closed.

[lynxplay]

I'll throw it at some other team members too but yea, I don't see much usecase for exposing this.
But maybe I am wrong so, lets wait on some more input 😅