refactor: Add new Parse Server option fileUpload.fileExtensions to restrict file upload by file extension (#8539)

src/Options/index.js

@@ -540,6 +540,9 @@ export interface PasswordPolicyOptions {
 }
 
 export interface FileUploadOptions {
+  /* Sets the allowed file extensions for uploading files. The extension is defined as an array of file extensions, or a regex pattern.<br><br>It is recommended to restrict the file upload extensions as much as possible. HTML files are especially problematic as they may be used by an attacker who uploads a HTML form to look legitimate under your app's domain name, or to compromise the session token of another user via accessing the browser's local storage.<br><br>Defaults to `^[^hH][^tT][^mM][^lL]?$` which allows any file extension except HTML files.
+  :DEFAULT: ["^[^hH][^tT][^mM][^lL]?$"] */
+  fileExtensions: ?(string[]);
   /*  Is true if file upload should be allowed for anonymous users.
   :DEFAULT: false */
   enableForAnonymousUser: ?boolean;