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/comp/ImagePaste.js

@@ -59,7 +59,7 @@ export function initCompImagePaste($target) {
     if (!dropzone) {
       return;
     }
-    const uploadUrl = dropzone.dataset.uploadUrl;
+    const uploadUrl = dropzone.getAttribute('data-upload-url');
     const dropzoneFiles = dropzone.querySelector('.files');
     for (const textarea of this.querySelectorAll('textarea')) {
       textarea.addEventListener('paste', async (e) => {
@@ -77,7 +77,7 @@ export function initCompImagePaste($target) {
 }
 
 export function initSimpleMDEImagePaste(simplemde, dropzone, files) {
-  const uploadUrl = dropzone.dataset.uploadUrl;
+  const uploadUrl = dropzone.getAttribute('data-upload-url');
   simplemde.codemirror.on('paste', async (_, e) => {
     for (const img of clipboardPastedImages(e)) {
       const name = img.name.substr(0, img.name.lastIndexOf('.'));