Make `cwd` configurable per adapter

[flunderpero]

I have a monorepo and need my vitest files to be run at the project root. Because currently the adapter searches for the next package.json up the path, it is run in the package directory, not project root.

I think this might be a common problem with monorepos. In my case the solution would be to search for vite.config.ts instead of package.json but that might not be always the case, so having cwd as a configurable function would be great.

[quolpr]

Thanks for the issue! This commit should fix it https://github.com/quolpr/quicktest.nvim/commit/cb5d6c84b4633ca86bd60d484ab6b1d3dc2b6f9b