Replace underscore/lodash in design_management

This replaces all underscore usage for lodash inside
the EE feature design_management

ee/app/assets/javascripts/design_management/components/delete_button.vue

 <script>
 import { GlButton, GlModal, GlModalDirective } from '@gitlab/ui';
-import _ from 'underscore';
+import { uniqueId } from 'lodash';
 
 export default {
   name: 'DeleteButton',
@@ -35,7 +35,7 @@ export default {
   },
   data() {
     return {
-      modalId: _.uniqueId('design-deletion-confirmation-'),
+      modalId: uniqueId('design-deletion-confirmation-'),
     };
   },
 };

ee/app/assets/javascripts/design_management/components/design_presentation.vue

 <script>
-import _ from 'underscore';
+import { throttle } from 'lodash';
 import DesignImage from './image.vue';
 import DesignOverlay from './design_overlay.vue';
 
@@ -66,7 +66,7 @@ export default {
     const { presentationViewport } = this.$refs;
     if (!presentationViewport) return;
 
-    this.scrollThrottled = _.throttle(() => {
+    this.scrollThrottled = throttle(() => {
       this.shiftZoomFocalPoint();
     }, 400);
 

ee/app/assets/javascripts/design_management/components/image.vue

 <script>
-import _ from 'underscore';
+import { throttle } from 'lodash';
 
 export default {
   props: {
@@ -36,7 +36,7 @@ export default {
   mounted() {
     this.onImgLoad();
 
-    this.resizeThrottled = _.throttle(() => {
+    this.resizeThrottled = throttle(() => {
       // NOTE: if imageStyle is set, then baseImageSize
       // won't change due to resize. We must still emit a
       // `resize` event so that the parent can handle

ee/app/assets/javascripts/design_management/graphql.js

 import Vue from 'vue';
 import VueApollo from 'vue-apollo';
-import _ from 'underscore';
+import { uniqueId } from 'lodash';
 import { defaultDataIdFromObject } from 'apollo-cache-inmemory';
 import createDefaultClient from '~/lib/graphql';
 
@@ -15,7 +15,7 @@ const defaultClient = createDefaultClient(
       dataIdFromObject: object => {
         // eslint-disable-next-line no-underscore-dangle, @gitlab/require-i18n-strings
         if (object.__typename === 'Design') {
-          return object.id && object.image ? `${object.id}-${object.image}` : _.uniqueId();
+          return object.id && object.image ? `${object.id}-${object.image}` : uniqueId();
         }
         return defaultDataIdFromObject(object);
       },

ee/app/assets/javascripts/design_management/mixins/all_designs.js

-import { propertyOf } from 'underscore';
+import { propertyOf } from 'lodash';
 import createFlash from '~/flash';
 import { s__ } from '~/locale';
 import projectQuery from '../graphql/queries/project.query.graphql';

ee/app/assets/javascripts/design_management/utils/design_management_utils.js

-import { uniqueId } from 'underscore';
+import { uniqueId } from 'lodash';
 import { VALID_DESIGN_FILE_MIMETYPE } from '../constants';
 
 export const isValidDesignFile = ({ type }) =>

ee/spec/frontend/design_management/utils/design_management_utils_spec.js

-import underscore from 'underscore';
 import {
   extractCurrentDiscussion,
   extractDiscussions,
@@ -8,6 +7,8 @@ import {
   isValidDesignFile,
 } from 'ee/design_management/utils/design_management_utils';
 
+jest.mock('lodash/uniqueId', () => () => 1);
+
 describe('extractCurrentDiscussion', () => {
   let discussions;
 
@@ -75,7 +76,6 @@ describe('version parser', () => {
 
 describe('optimistic responses', () => {
   it('correctly generated for designManagementUpload', () => {
-    jest.spyOn(underscore, 'uniqueId').mockImplementation(() => 1);
     const expectedResponse = {
       __typename: 'Mutation',
       designManagementUpload: {