Convert frontend code to typescript (#31559)

None of the frontend js/ts files was touched besides these two commands
(edit: no longer true, I touched one file in
61105d0618
because of a deprecation that was not showing before the rename).

`tsc` currently reports 778 errors, so I have disabled it in CI as
planned.

Everything appears to work fine.

web_src/js/features/comp/ComboMarkdownEditor.ts

@@ -1,17 +1,17 @@
 import '@github/markdown-toolbar-element';
 import '@github/text-expander-element';
 import $ from 'jquery';
-import {attachTribute} from '../tribute.js';
-import {hideElem, showElem, autosize, isElemVisible} from '../../utils/dom.js';
-import {initEasyMDEPaste, initTextareaUpload} from './EditorUpload.js';
-import {handleGlobalEnterQuickSubmit} from './QuickSubmit.js';
-import {renderPreviewPanelContent} from '../repo-editor.js';
-import {easyMDEToolbarActions} from './EasyMDEToolbarActions.js';
-import {initTextExpander} from './TextExpander.js';
-import {showErrorToast} from '../../modules/toast.js';
-import {POST} from '../../modules/fetch.js';
-import {initTextareaMarkdown} from './EditorMarkdown.js';
-import {DropzoneCustomEventReloadFiles, initDropzone} from '../dropzone.js';
+import {attachTribute} from '../tribute.ts';
+import {hideElem, showElem, autosize, isElemVisible} from '../../utils/dom.ts';
+import {initEasyMDEPaste, initTextareaUpload} from './EditorUpload.ts';
+import {handleGlobalEnterQuickSubmit} from './QuickSubmit.ts';
+import {renderPreviewPanelContent} from '../repo-editor.ts';
+import {easyMDEToolbarActions} from './EasyMDEToolbarActions.ts';
+import {initTextExpander} from './TextExpander.ts';
+import {showErrorToast} from '../../modules/toast.ts';
+import {POST} from '../../modules/fetch.ts';
+import {initTextareaMarkdown} from './EditorMarkdown.ts';
+import {DropzoneCustomEventReloadFiles, initDropzone} from '../dropzone.ts';
 
 let elementIdCounter = 0;
 

web_src/js/features/comp/ConfirmModal.ts

@@ -1,7 +1,7 @@
 import $ from 'jquery';
-import {svg} from '../../svg.js';
+import {svg} from '../../svg.ts';
 import {htmlEscape} from 'escape-goat';
-import {createElementFromHTML} from '../../utils/dom.js';
+import {createElementFromHTML} from '../../utils/dom.ts';
 
 const {i18n} = window.config;
 

web_src/js/features/comp/EasyMDEToolbarActions.ts

@@ -1,4 +1,4 @@
-import {svg} from '../../svg.js';
+import {svg} from '../../svg.ts';
 
 export function easyMDEToolbarActions(EasyMDE, editor) {
   const actions = {

web_src/js/features/comp/EditorUpload.test.ts

@@ -1,4 +1,4 @@
-import {removeAttachmentLinksFromMarkdown} from './EditorUpload.js';
+import {removeAttachmentLinksFromMarkdown} from './EditorUpload.ts';
 
 test('removeAttachmentLinksFromMarkdown', () => {
   expect(removeAttachmentLinksFromMarkdown('a foo b', 'foo')).toBe('a foo b');

web_src/js/features/comp/EditorUpload.ts

@@ -1,12 +1,12 @@
-import {imageInfo} from '../../utils/image.js';
-import {replaceTextareaSelection} from '../../utils/dom.js';
-import {isUrl} from '../../utils/url.js';
-import {triggerEditorContentChanged} from './EditorMarkdown.js';
+import {imageInfo} from '../../utils/image.ts';
+import {replaceTextareaSelection} from '../../utils/dom.ts';
+import {isUrl} from '../../utils/url.ts';
+import {triggerEditorContentChanged} from './EditorMarkdown.ts';
 import {
   DropzoneCustomEventRemovedFile,
   DropzoneCustomEventUploadDone,
   generateMarkdownLinkForAttachment,
-} from '../dropzone.js';
+} from '../dropzone.ts';
 
 let uploadIdCounter = 0;
 

web_src/js/features/comp/ReactionSelector.ts

@@ -1,5 +1,5 @@
 import $ from 'jquery';
-import {POST} from '../../modules/fetch.js';
+import {POST} from '../../modules/fetch.ts';
 
 export function initCompReactionSelector() {
   for (const container of document.querySelectorAll('.issue-content, .diff-file-body')) {

web_src/js/features/comp/TextExpander.ts

@@ -1,5 +1,5 @@
-import {matchEmoji, matchMention} from '../../utils/match.js';
-import {emojiString} from '../emoji.js';
+import {matchEmoji, matchMention} from '../../utils/match.ts';
+import {emojiString} from '../emoji.ts';
 
 export function initTextExpander(expander) {
   expander?.addEventListener('text-expander-change', ({detail: {key, provide, text}}) => {

web_src/js/features/comp/WebHookEditor.ts

@@ -1,5 +1,5 @@
-import {POST} from '../../modules/fetch.js';
-import {hideElem, showElem, toggleElem} from '../../utils/dom.js';
+import {POST} from '../../modules/fetch.ts';
+import {hideElem, showElem, toggleElem} from '../../utils/dom.ts';
 
 export function initCompWebHookEditor() {
   if (!document.querySelectorAll('.new.webhook').length) {