fix(types): add some return/parameter type annotations (#24867)

* fix(types): add some return/parameter type annotations

* fix(types): narrow stdpath parameter further

runtime/lua/vim/_editor.lua

@@ -188,6 +188,7 @@ end
 ---@see |vim.print()|
 ---@see https://github.com/kikito/inspect.lua
 ---@see https://github.com/mpeterv/vinspect
+---@return string
 vim.inspect = vim.inspect
 
 do