Replace the busted-based Lua test runner with a repo-local harness.
The new harness runs spec files directly under `nvim -ll`, ships its own
reporter and lightweight `luassert` shim, and keeps the helper/preload
flow used by the functional and unit test suites.
Keep the file boundary model shallow and busted-like by restoring `_G`,
`package.loaded`, `package.preload`, `arg`, and the process environment
between files, without carrying extra reset APIs or custom assertion
machinery.
Update the build and test entrypoints to use the new runner, add
black-box coverage for the harness itself, and drop the bundled
busted/luacheck dependency path.
AI-assisted: Codex
This reverts a large portion of
2c1e8f7e96.
The conclusion from that commit is incorrect: local builds are not
used/updated correctly so much as it's not used at all. Instead the
build will always use `master` branch rather than the current files.
`GIT_REPOSITORY` will cause cmake to rebuild if local dependency
changes, which isn't the case for `URL`.
Also document how to test a different commits of a dependency.
This will reduce friction as developers no longer need to provide a hash
when testing out different commits.
To skip the hash check, set `DEPS_IGNORE_SHA` to `TRUE` in
`cmake.deps/CMakeLists.txt`.
Downloading the necessary files all at once instead of doing dependency
handling with luarocks speeds up installation immensely. We speed up the
process even more by using luv as a replacement for the C modules in the
busted dependencies, which allows us to skip costly compilation times.
Co-authored-by: bfredl <bjorn.linse@gmail.com>
Uncrustify is sensitive to version changes, which causes friction for
contributors that doesn't have that exact version. It's also simpler to
download and install the correct version than to have bespoke version
checking.
