build: rework ci tests to include windows

[jamestrew]

• add windows runner as part of test ci and fix any windows sensitive tests
• tweak Makefile & minimal_init so running tests locally isn't dependent on local directory structure (I wanted to do this with docgen as well but it's so flaky and impossible on nightly neovim anyways)

close #3000

ps. sorry if you got spammed by failed ci notifs

[jamestrew]

macos nightly failure: rhysd/action-setup-vim#30

[Conni2461]

Yeah generally speaking we can add a windows test runner. Currently no checks did run. is this correct?

Edit: found it nvm, forgot about that 😅

tweak Makefile & minimal_init so running tests locally isn't dependent on local directory structure (I wanted to do this with docgen as well but it's so flaky and impossible on nightly neovim anyways)

This is the only thing i actually dont like. We never wanna download dependencies for the user who runs the tests locally. We only wanna do this in an controlled environment, github runner. This was never an issue in the past 2.5 years so i dont see a reason to change that, users who actually have a different directory structure, should probably just manually edit the minimal rc. Thats far simpler than dealing with a "complex" Makefile which is a pain (see telescope-fzf-native.nvim, which only has to compile a singe c source file ...)

[Conni2461]

thanks :)