* Update _TerminalCursorPositionChanged to use ThrottledFunc.
* Rename previous ThrottledFunc to ThrottledArgFunc because now
ThrottledFunc is for functions that do not take an argument.
* Update ThrottledFunc and ThrottledArgFunc to accept a CoreDispatcher
on which the function should be called for convenience.
* Don't use coroutines/winrt::fire_and_forget in
ThrottledFunc/ThrottledArgFunc because they are too slow (see PR).
_AdjustCursorPosition went from 17% of samples to 3% in performance
testing.
