Keep Monaco in conditional imports

To avoid significant increase in webpack modules,
make sure Monaco imports are localized in the
conditionally loaded modules

app/assets/javascripts/blob/file_template_mediator.js

 import $ from 'jquery';
-import { Position } from 'monaco-editor';
 
 import Api from '~/api';
 import toast from '~/vue_shared/plugins/global_toast';
@@ -191,14 +190,7 @@ export default class FileTemplateMediator {
 
     this.editor.focus();
 
-    if (this.editor.navigateFileStart) {
-      // ACE. This will be removed and cleaned up
-      // in https://gitlab.com/gitlab-org/gitlab/-/issues/198610
-      this.editor.navigateFileStart();
-    } else {
-      // Editor Lite
-      this.editor.setPosition(new Position(1, 1));
-    }
+    this.editor.navigateFileStart();
   }
 
   findTemplateSelectorByKey(key) {

app/assets/javascripts/blob_edit/edit_blob.js

@@ -40,9 +40,10 @@ export default class EditBlob {
     const MarkdownExtensionPromise = this.options.isMarkdown
       ? import('~/editor/editor_markdown_ext')
       : Promise.resolve(false);
+    const FileTemplateExtensionPromise = import('~/editor/editor_file_template_ext');
 
-    return Promise.all([EditorPromise, MarkdownExtensionPromise])
-      .then(([EditorModule, MarkdownExtension]) => {
+    return Promise.all([EditorPromise, MarkdownExtensionPromise, FileTemplateExtensionPromise])
+      .then(([EditorModule, MarkdownExtension, FileTemplateExtension]) => {
         const EditorLite = EditorModule.default;
         const editorEl = document.getElementById('editor');
         const fileNameEl =
@@ -58,9 +59,7 @@ export default class EditBlob {
           blobContent: editorEl.innerText,
         });
 
-        if (MarkdownExtension) {
-          rootEditor.use(MarkdownExtension.default, this.editor);
-        }
+        rootEditor.use([MarkdownExtension.default, FileTemplateExtension.default], this.editor);
 
         fileNameEl.addEventListener('change', () => {
           this.editor.updateModelLanguage(fileNameEl.value);

app/assets/javascripts/editor/editor_file_template_ext.js

+import { Position } from 'monaco-editor';
+
+export default {
+  navigateFileStart() {
+    this.setPosition(new Position(1, 1));
+  },
+};

app/assets/javascripts/editor/editor_lite.js

@@ -73,7 +73,6 @@ export default class Editor {
       this.instances.splice(index, 1);
       model.dispose();
     });
-
     instance.updateModelLanguage = path => this.updateModelLanguage(path);
 
     // Reference to the model on the editor level will go away in

spec/frontend/blob_edit/edit_blob_spec.js

 import EditBlob from '~/blob_edit/edit_blob';
 import EditorLite from '~/editor/editor_lite';
 import MarkdownExtension from '~/editor/editor_markdown_ext';
+import FileTemplateExtension from '~/editor/editor_file_template_ext';
 
 jest.mock('~/editor/editor_lite');
 jest.mock('~/editor/editor_markdown_ext');
@@ -21,13 +22,29 @@ describe('Blob Editing', () => {
     });
   };
 
-  it('does not load MarkdownExtension by default', async () => {
+  it('loads FileTemplateExtension by default', async () => {
     await initEditor();
-    expect(EditorLite.prototype.use).not.toHaveBeenCalled();
+    expect(EditorLite.prototype.use).toHaveBeenCalledWith(
+      expect.arrayContaining([FileTemplateExtension]),
+      mockInstance,
+    );
   });
 
-  it('loads MarkdownExtension only for the markdown files', async () => {
-    await initEditor(true);
-    expect(EditorLite.prototype.use).toHaveBeenCalledWith(MarkdownExtension, mockInstance);
+  describe('Markdown', () => {
+    it('does not load MarkdownExtension by default', async () => {
+      await initEditor();
+      expect(EditorLite.prototype.use).not.toHaveBeenCalledWith(
+        expect.arrayContaining([MarkdownExtension]),
+        mockInstance,
+      );
+    });
+
+    it('loads MarkdownExtension only for the markdown files', async () => {
+      await initEditor(true);
+      expect(EditorLite.prototype.use).toHaveBeenCalledWith(
+        [MarkdownExtension, FileTemplateExtension],
+        mockInstance,
+      );
+    });
   });
 });