feat: cmp async (#1583)

lua/cmp/types/cmp.lua

@@ -99,6 +99,8 @@ cmp.ItemField = {
 ---@field public debounce integer
 ---@field public throttle integer
 ---@field public fetching_timeout integer
+---@field public async_budget integer Maximum time (in ms) an async function is allowed to run during one step of the event loop.
+---@field public max_view_entries integer
 
 ---@class cmp.WindowConfig
 ---@field completion cmp.WindowConfig