Feature request: 2D grid navigation

Back in the day we had 2D [Spaces](https://en.wikipedia.org/wiki/Spaces_(software)) in [Mac OS X](https://en.wikipedia.org/wiki/MacOS#Mac_OS_X), but that was removed for unknown reasons. Then the excellent [TotalSpaces2](https://totalspaces.binaryage.com/) came and rescued the day, but today [that doesn't work anymore](https://github.com/koekeishiya/yabai/discussions/1683#discussion-5014825).

Now we have yabai which is excellent, but we don't have 2D grid navigation. Therefore, I've taken a stab at adding “Grid navigation” to Yabai, https://github.com/koekeishiya/yabai/pull/2601, and I've been using it myself for quite some time.

Start by reading pull request #2601, which contains the proposed grid-navigation implementation, and review the linked discussion about current TotalSpaces2 behavior. Done would mean determining whether that existing work should be continued or adapted into yabai, with the resulting navigation behavior validated on macOS.

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