Rename utils/worker to tree_worker_utils

- This way we avoid some abiguity since
  these functions are only ever used by
  the tree_worker.

app/assets/javascripts/diffs/workers/tree_worker.js

 import { sortTree } from '~/ide/stores/utils';
-import { generateTreeList } from '../utils/workers';
+import { generateTreeList } from '../utils/tree_worker_utils';
 
 // eslint-disable-next-line no-restricted-globals
 self.addEventListener('message', (e) => {

spec/frontend/diffs/store/actions_spec.js

@@ -51,7 +51,7 @@ import {
 } from '~/diffs/store/actions';
 import * as types from '~/diffs/store/mutation_types';
 import * as utils from '~/diffs/store/utils';
-import * as workerUtils from '~/diffs/utils/workers';
+import * as treeWorkerUtils from '~/diffs/utils/tree_worker_utils';
 import createFlash from '~/flash';
 import axios from '~/lib/utils/axios_utils';
 import * as commonUtils from '~/lib/utils/common_utils';
@@ -253,7 +253,7 @@ describe('DiffsStoreActions', () => {
           // Workers are synchronous in Jest environment (see https://gitlab.com/gitlab-org/gitlab/-/merge_requests/58805)
           {
             type: types.SET_TREE_DATA,
-            payload: workerUtils.generateTreeList(diffMetadata.diff_files),
+            payload: treeWorkerUtils.generateTreeList(diffMetadata.diff_files),
           },
         ],
         [],

spec/frontend/diffs/utils/workers_spec.js → spec/frontend/diffs/utils/tree_worker_utils_spec.js

-import { generateTreeList, getLowestSingleFolder, flattenTree } from '~/diffs/utils/workers';
+import {
+  generateTreeList,
+  getLowestSingleFolder,
+  flattenTree,
+} from '~/diffs/utils/tree_worker_utils';
 
-describe('~/diffs/utils/workers', () => {
+describe('~/diffs/utils/tree_worker_utils', () => {
   describe('generateTreeList', () => {
     let files;