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>

build/generate-images.js

@@ -80,5 +80,5 @@ async function main() {
   ]);
 }
 
-main().then(exit).catch(exit);
+main().then(exit).catch(exit); // eslint-disable-line github/no-then
 

build/generate-svg.js

@@ -54,5 +54,5 @@ async function main() {
   ]);
 }
 
-main().then(exit).catch(exit);
+main().then(exit).catch(exit); // eslint-disable-line github/no-then