rework eslint config (#11615)

* rework eslint config

- use explicit config that only enables rules
- upgrade eslint to 7.1.0
- add new plugins with selected rules enabled
- fix discovered issues, remove global wipPrefixes

* remove if

* undo template change

* add disabled rules as well for easier config updating

* add missing disabled rule

* update eslint and plugins

* fix new violation

* remove deprecated rules

Co-authored-by: Lauris BH <lauris@nix.lv>

web_src/js/features/highlight.worker.js

@@ -1,7 +1,7 @@
 import {highlightBlock} from 'highlight.js';
 import {createWindow} from 'domino';
 
-self.onmessage = function ({data}) {
+self.addEventListener('message', ({data}) => {
   const window = createWindow();
   self.document = window.document;
 
@@ -9,4 +9,4 @@ self.onmessage = function ({data}) {
   document.body.innerHTML = html;
   highlightBlock(document.body.firstChild);
   self.postMessage({index, html: document.body.innerHTML});
-};
+});