Enable the unicorn/prefer-dom-node-append ESLint plugin rule

This rule will help enforce slightly shorter code, especially since you can insert multiple elements at once, and according to MDN `Element.append()` is available in all browsers that we currently support.

Please find additional information here:
 - https://developer.mozilla.org/en-US/docs/Web/API/Element/append
 - https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/prefer-dom-node-append.md

src/display/editor/ink.js

@@ -353,7 +353,7 @@ class InkEditor extends AnnotationEditor {
   #createCanvas() {
     this.canvas = document.createElement("canvas");
     this.canvas.className = "inkEditorCanvas";
-    this.div.appendChild(this.canvas);
+    this.div.append(this.canvas);
     this.ctx = this.canvas.getContext("2d");
   }