Use lodash in filtered_search components

This MR replaces underscope with lodash
in filtered_search files

app/assets/javascripts/filtered_search/dropdown_utils.js

-import _ from 'underscore';
+import { last } from 'lodash';
 import FilteredSearchContainer from './container';
 import FilteredSearchTokenizer from './filtered_search_tokenizer';
 import FilteredSearchDropdownManager from './filtered_search_dropdown_manager';
@@ -70,11 +70,11 @@ export default class DropdownUtils {
 
     if (!allowMultiple && itemInExistingTokens) {
       updatedItem.droplab_hidden = true;
-    } else if (!isSearchItem && (!lastKey || _.last(searchInput.split('')) === ' ')) {
+    } else if (!isSearchItem && (!lastKey || last(searchInput.split('')) === ' ')) {
       updatedItem.droplab_hidden = false;
     } else if (lastKey) {
       const split = lastKey.split(':');
-      const tokenName = _.last(split[0].split(' '));
+      const tokenName = last(split[0].split(' '));
 
       const match = isSearchItem
         ? allowedKeys.some(key => key.startsWith(tokenName.toLowerCase()))
@@ -129,7 +129,7 @@ export default class DropdownUtils {
     const values = [];
 
     if (untilInput) {
-      const inputIndex = _.findIndex(tokens, t => t.classList.contains('input-token'));
+      const inputIndex = tokens.findIndex(t => t.classList.contains('input-token'));
       // Add one to include input-token to the tokens array
       tokens.splice(inputIndex + 1);
     }

app/assets/javascripts/filtered_search/filtered_search_dropdown_manager.js

+import { last } from 'lodash';
 import AvailableDropdownMappings from 'ee_else_ce/filtered_search/available_dropdown_mappings';
-import _ from 'underscore';
 import DropLab from '~/droplab/drop_lab';
 import FilteredSearchContainer from './container';
 import FilteredSearchTokenKeys from './filtered_search_token_keys';
@@ -184,8 +184,8 @@ export default class FilteredSearchDropdownManager {
       // Eg. token = 'label:'
 
       const split = lastToken.split(':');
-      const dropdownName = _.last(split[0].split(' '));
-      const possibleOperatorToken = _.last(split[1]);
+      const dropdownName = last(split[0].split(' '));
+      const possibleOperatorToken = last(split[1]);
 
       const hasOperator = FilteredSearchVisualTokens.permissibleOperatorValues.includes(
         possibleOperatorToken && possibleOperatorToken.trim(),

app/assets/javascripts/filtered_search/filtered_search_manager.js

-import _ from 'underscore';
+import { last } from 'lodash';
 import recentSearchesStorageKeys from 'ee_else_ce/filtered_search/recent_searches_storage_keys';
 import { getParameterByName, getUrlParamsArray } from '~/lib/utils/common_utils';
 import IssuableFilteredSearchTokenKeys from '~/filtered_search/issuable_filtered_search_token_keys';
@@ -456,7 +456,7 @@ export default class FilteredSearchManager {
 
       if (fragments.length > 1) {
         const inputValues = fragments[0].split(' ');
-        const tokenKey = _.last(inputValues);
+        const tokenKey = last(inputValues);
 
         if (inputValues.length > 1) {
           inputValues.pop();

app/assets/javascripts/filtered_search/issuable_filtered_search_token_keys.js

-import { flatten } from 'underscore';
+import { flattenDeep } from 'lodash';
 import FilteredSearchTokenKeys from './filtered_search_token_keys';
 import { __ } from '~/locale';
 
@@ -73,7 +73,7 @@ export const alternativeTokenKeys = [
   },
 ];
 
-export const conditions = flatten(
+export const conditions = flattenDeep(
   [
     {
       url: 'assignee_id=None',

app/assets/javascripts/filtered_search/stores/recent_searches_store.js

-import _ from 'underscore';
+import { uniq } from 'lodash';
 
 class RecentSearchesStore {
   constructor(initialState = {}, allowedKeys) {
@@ -20,7 +20,7 @@ class RecentSearchesStore {
 
   setRecentSearches(searches = []) {
     const trimmedSearches = searches.map(search => search.trim());
-    this.state.recentSearches = _.uniq(trimmedSearches).slice(0, 5);
+    this.state.recentSearches = uniq(trimmedSearches).slice(0, 5);
     return this.state.recentSearches;
   }
 }

app/assets/javascripts/filtered_search/visual_token_value.js

-import _ from 'underscore';
+import { escape as esc } from 'lodash';
 import { USER_TOKEN_TYPES } from 'ee_else_ce/filtered_search/constants';
 import FilteredSearchContainer from '~/filtered_search/container';
 import FilteredSearchVisualTokens from '~/filtered_search/filtered_search_visual_tokens';
@@ -48,7 +48,7 @@ export default class VisualTokenValue {
           tokenValueContainer.dataset.originalValue = tokenValue;
           tokenValueElement.innerHTML = `
           <img class="avatar s20" src="${user.avatar_url}" alt="">
-          ${_.escape(user.name)}
+          ${esc(user.name)}
         `;
           /* eslint-enable no-param-reassign */
         })