feat: implement AddCohart modal component with multi-step form for cohort creation and editing

src/app/cohartManage/components/AddCohart.tsx

@@ -1,4 +1,4 @@
-import React, { useState, useEffect, useMemo, useRef } from 'react';
+import React, { useState, useEffect} from 'react';
 import { FileTextIcon, CaretRightIcon, CaretLeftIcon, UserListIcon, GlobeIcon, UserCircleCheckIcon } from '@phosphor-icons/react';
 import {
   CustomModal,