chore: update eslint, enable more rules and fix their findings (#39438)

Update eslint and its plugins, enable more rules and fix their findings:

1. `unicorn/no-unsafe-string-replacement` found that uploading a file
whose name contains `$&` inserted a broken markdown link, because
`String#replace` expands such patterns in the replacement string
2. `@typescript-eslint/require-await` removes `async` from functions
that never await
3. Plugin rules not covered by a preset are now listed explicitly

---------

Co-authored-by: bircni <bircni@icloud.com>

web_src/js/modules/toast.test.ts

@@ -1,21 +1,21 @@
 import {showSuccessToast, showInfoToast, showErrorToast, showWarningToast} from './toast.ts';
 
-test('showSuccessToast', async () => {
+test('showSuccessToast', () => {
   showSuccessToast('success', {duration: -1});
   expect(document.querySelector('.toastify')).toBeTruthy();
 });
 
-test('showInfoToast', async () => {
+test('showInfoToast', () => {
   showInfoToast('info', {duration: -1});
   expect(document.querySelector('.toastify')).toBeTruthy();
 });
 
-test('showWarningToast', async () => {
+test('showWarningToast', () => {
   showWarningToast('warning', {duration: -1});
   expect(document.querySelector('.toastify')).toBeTruthy();
 });
 
-test('showErrorToast', async () => {
+test('showErrorToast', () => {
   showErrorToast('error', {duration: -1});
   expect(document.querySelector('.toastify')).toBeTruthy();
 });