fix: add package.path, package.cpath only for lazy.nvim

[black-desk]

Why this is a fix?

[Freed-Wu]

If only lazy.nvim need to add these paths, perhaps we can avoid add them for other users to keep a clean package.path.

[black-desk]

I mean that it make more sense to be a "refact" than a "fix"

[Freed-Wu]

OK, done.