[Editor] Unselect correctly removed editors

- After undoing a deletion of several editors, they appeared to be selected (they had a red border)
when in fact they were not, consequently, this patch aims to remove the selectedEditor class when
an editor is removed;
- Add a test with some ink editors.

src/display/editor/ink.js

@@ -416,6 +416,9 @@ class InkEditor extends AnnotationEditor {
     // When commiting, the position of this editor is changed, hence we must
     // move it to the right position in the DOM.
     this.parent.moveDivInDOM(this);
+    // After the div has been moved in the DOM, the focus may have been stolen
+    // by document.body, hence we just keep it here.
+    this.div.focus();
   }
 
   /** @inheritdoc */