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/heatmap.js

@@ -8,11 +8,11 @@ export default function initHeatmap() {
 
   try {
     const heatmap = {};
-    JSON.parse(el.dataset.heatmapData).forEach(({contributions, timestamp}) => {
+    for (const {contributions, timestamp} of JSON.parse(el.getAttribute('data-heatmap-data'))) {
       // Convert to user timezone and sum contributions by date
       const dateStr = new Date(timestamp * 1000).toDateString();
       heatmap[dateStr] = (heatmap[dateStr] || 0) + contributions;
-    });
+    }
 
     const values = Object.keys(heatmap).map((v) => {
       return {date: new Date(v), count: heatmap[v]};