Add time.Sleep()

[JothamWong]

Adds the time.Sleep(duration) in milliseconds standard library implementation.

Tested with time yarn booga on

time.Sleep(10000);

[JothamWong]

Have to remember that everytime we add standard library implementations, our Garbage Collection tests that operated on the bare edge need to be updated as well.
A smarter fix is to simply obtain the min number of words required for initialization and then programmatically add that to the number of words for the GC tests but I am not gonna do this right now.