Sanitize user-input on file name (#17666)

* Sanitize user-input on file name

- Sanitize user-input before it get passed into the DOM.
- Prevent things like "<iframe onload=alert(1)></iframe>" from being
executed. This isn't a XSS attack as the server seems to be santizing
the path as well.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

web_src/js/features/repo-editor.js

+import {htmlEscape} from 'escape-goat';
 import {initMarkupContent} from '../markup/content.js';
 import {createCodeEditor} from './codeeditor.js';
 
         value = parts[i];
         if (i < parts.length - 1) {
           if (value.length) {
-            $(`<span class="section"><a href="#">${value}</a></span>`).insertBefore($(this));
+            $(`<span class="section"><a href="#">${htmlEscape(value)}</a></span>`).insertBefore($(this));
             $('<div class="divider"> / </div>').insertBefore($(this));
           }
         } else {