Add new JS linter rules (#17699)

* Add new JS linter rules

Adds a few useful rules from eslint-plugin-github. Notable changes:

- Forbid dataset usage, its camel-casing behaviour makes it hard to
  grep for attributes.
- Forbid .then() and .catch(), we should generally prefer await for new
  code. For rare cases where they are useful, a eslint-disable-line
  directive can be set.
- Add docs js to linting

* also enable github/array-foreach

* small tweak

Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

web_src/js/features/user-auth-u2f.js

@@ -1,3 +1,4 @@
+/* eslint-disable github/no-then */
 const {appSubUrl, csrfToken} = window.config;
 
 export function initUserAuthU2fAuth() {
@@ -77,11 +78,11 @@ function u2fError(errorType) {
   };
   u2fErrors[errorType].removeClass('hide');
 
-  Object.keys(u2fErrors).forEach((type) => {
+  for (const type of Object.keys(u2fErrors)) {
     if (type !== `${errorType}`) {
       u2fErrors[type].addClass('hide');
     }
-  });
+  }
   $('#u2f-error').modal('show');
 }