make debounce and throttle time configurable (#1026)

* make debounce and throttle time configurable

* fix documentation

lua/cmp/types/cmp.lua

@@ -80,6 +80,7 @@ cmp.ItemField = {
 ---@class cmp.ConfigSchema
 ---@field private revision number
 ---@field public enabled fun():boolean|boolean
+---@field public performance cmp.PerformanceConfig
 ---@field public preselect cmp.PreselectMode
 ---@field public completion cmp.CompletionConfig
 ---@field public window cmp.WindowConfig|nil
@@ -93,6 +94,10 @@ cmp.ItemField = {
 ---@field public view cmp.ViewConfig
 ---@field public experimental cmp.ExperimentalConfig
 
+---@class cmp.PerformanceConfig
+---@field public debounce number
+---@field public throttle number
+
 ---@class cmp.WindowConfig
 ---@field completion cmp.WindowConfig
 ---@field documentation cmp.WindowConfig|nil