word diff regression

[phanen]

• chore: word_diff regresion
• test: diff.has_vscode() fail

word_diff seems missing again (neovim/neovim#31151)

Not sure how to fix the test, so take this as a bug report.

[phanen]

There're a few other choice for fine grid extmark test:

• screenattr() also used in mini.test, but can be flaky to nvim version bump
• ext_linegrid ui client a bit complex here, since this require subprocesses https://github.com/neovim/neovim/blob/d0c699ec7b0fe6f942536b8241e35575f3b9d5ff/test/functional/ui/screen.lua
• nvim__inspect_cell() non-stable, for float window it need to "search" for the correct "grid"

[barrettruth]

damnit. sorry about this. going to see what i can do.

[barrettruth]

#192