compositor: only delay hardware cursor updates when necessary

Xaver Huglrequested to merge
work/zamundaaa/cursor-vrr-delay into master 
We only want to delay them while an active window is driving the refresh rate of
the screen - outside of that situation, we want cursor updates to be done at the
maximum refresh rate of the screen.

BUG: 487563

The other two commits are refactors to make it possible for the Compositor to control this.

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