Lazy load components in issues list refactor page

Some components are shown conditionally, so they have been changed
to load lazily to reduce the bundle size for the page.

This change is behind the feature flag `vue_issues_list`.

https://gitlab.com/gitlab-org/gitlab/-/issues/322755

app/assets/javascripts/issues_list/components/issues_list_app.vue

@@ -68,13 +68,6 @@ import {
   TOKEN_TITLE_TYPE,
   TOKEN_TITLE_WEIGHT,
 } from '~/vue_shared/components/filtered_search_bar/constants';
-import AuthorToken from '~/vue_shared/components/filtered_search_bar/tokens/author_token.vue';
-import EmojiToken from '~/vue_shared/components/filtered_search_bar/tokens/emoji_token.vue';
-import EpicToken from '~/vue_shared/components/filtered_search_bar/tokens/epic_token.vue';
-import IterationToken from '~/vue_shared/components/filtered_search_bar/tokens/iteration_token.vue';
-import LabelToken from '~/vue_shared/components/filtered_search_bar/tokens/label_token.vue';
-import MilestoneToken from '~/vue_shared/components/filtered_search_bar/tokens/milestone_token.vue';
-import WeightToken from '~/vue_shared/components/filtered_search_bar/tokens/weight_token.vue';
 import eventHub from '../eventhub';
 import reorderIssuesMutation from '../queries/reorder_issues.mutation.graphql';
 import searchIterationsQuery from '../queries/search_iterations.query.graphql';
@@ -84,6 +77,20 @@ import searchUsersQuery from '../queries/search_users.query.graphql';
 import IssueCardTimeInfo from './issue_card_time_info.vue';
 import NewIssueDropdown from './new_issue_dropdown.vue';
 
+const AuthorToken = () =>
+  import('~/vue_shared/components/filtered_search_bar/tokens/author_token.vue');
+const EmojiToken = () =>
+  import('~/vue_shared/components/filtered_search_bar/tokens/emoji_token.vue');
+const EpicToken = () => import('~/vue_shared/components/filtered_search_bar/tokens/epic_token.vue');
+const IterationToken = () =>
+  import('~/vue_shared/components/filtered_search_bar/tokens/iteration_token.vue');
+const LabelToken = () =>
+  import('~/vue_shared/components/filtered_search_bar/tokens/label_token.vue');
+const MilestoneToken = () =>
+  import('~/vue_shared/components/filtered_search_bar/tokens/milestone_token.vue');
+const WeightToken = () =>
+  import('~/vue_shared/components/filtered_search_bar/tokens/weight_token.vue');
+
 export default {
   i18n,
   IssuableListTabs,