Request: mouse follow focus command

I'd like to disable MFF on all windows by default, but I'd like the behavior to remain on all of my keyboard shortcuts that change which display/window is focused.

I dug though the code a bit (pretty easy to read!) and found the `window_manager_center_mouse` function. It'd be really cool if I could invoke that function via yabai: something like `yabai -m window --center-mouse`. I suppose right now what I could do is something like

```
yabai -m config mouse_follows_focus on; yabai existing command; yabai -m config mouse_follows_focus off;
```

For my keyboard shortcuts, though that is a bit cumbersome.

Start by locating the existing window_manager_center_mouse function and the dispatch path for yabai window commands. Add the requested --center-mouse invocation and verify that it centers the mouse on the focused window without changing the global mouse_follows_focus setting.

Written by the indexing model from the issue text.