feat(meta): vendor luv meta files

Problem: No type information for `vim.uv`.

Solution: Vendor https://github.com/LuaCATS/luv (which is what
luals bundles). This will allow other tooling to work out-of-the-box and
make these files available to users and plugins without the need for
`lazydev.nvim` etc.

runtime/lua/uv/_meta/luv_dir_t.lua

@@ -0,0 +1,36 @@
+---@meta
+-- luacheck: no unused args
+error('Cannot require a meta file')
+
+--- luv_dir_t
+---
+---@class uv.luv_dir_t : userdata
+local dir = {} -- luacheck: no unused
+
+--- Closes a directory stream returned by a successful `uv.fs_opendir()` call.
+---
+---@return boolean|nil success
+---@return uv.error.message|nil err
+---@return uv.error.name|nil err_name
+---
+---@overload fun(self:uv.luv_dir_t, callback:uv.fs_closedir.callback):uv.uv_fs_t
+function dir:closedir() end
+
+--- Iterates over the directory stream `luv_dir_t` returned by a successful
+--- `uv.fs_opendir()` call. A table of data tables is returned where the number
+--- of entries `n` is equal to or less than the `entries` parameter used in
+--- the associated `uv.fs_opendir()` call.
+---
+--- **Returns (sync version):** `table` or `fail`
+--- - `[1, 2, 3, ..., n]` : `table`
+---   - `name` : `string`
+---   - `type` : `string`
+---
+--- **Returns (async version):** `uv_fs_t userdata`
+---
+---@return uv.fs_readdir.entry[]|nil entries
+---@return uv.error.message|nil err
+---@return uv.error.name|nil err_name
+---
+---@overload fun(self:uv.luv_dir_t, callback:uv.fs_readdir.callback):uv.uv_fs_t
+function dir:readdir() end