Use explicit jQuery import, remove unused eslint globals (#18435)

- Don't rely on globals (window.$) for jQuery import
- Remove eslint globals no longer in use

web_src/js/components/ContextPopup.vue

@@ -24,6 +24,7 @@
 </template>
 
 <script>
+import $ from 'jquery';
 import {SvgIcon} from '../svg.js';
 
 const {appSubUrl, i18n} = window.config;

web_src/js/components/DashboardRepoList.js

@@ -1,4 +1,5 @@
 import Vue from 'vue';
+import $ from 'jquery';
 import {initVueSvg, vueDelimiters} from './VueComponentLoader.js';
 
 const {appSubUrl, assetUrlPrefix, pageData} = window.config;

web_src/js/components/RepoBranchTagDropdown.js

@@ -1,4 +1,5 @@
 import Vue from 'vue';
+import $ from 'jquery';
 import {vueDelimiters} from './VueComponentLoader.js';
 
 export function initRepoBranchTagDropdown(selector) {