Removes inert attribute when editorService.closeAll() is called

Fixes #10708 by removing the `inert` attribute on `#mainWrapper` when `editorService.closeAll()` is called.

This code is necessary because when close all is called, there is no editor passed, and so `removeEditor` is never called, and so the `focusLockService.removeInertAttribute();` method isn't called. I add to the if block that handles the close all code instead.

src/Umbraco.Web.UI.Client/src/common/directives/components/editor/umbeditors.directive.js

@@ -126,7 +126,9 @@
                 // close all editors
                 if (args && !args.editor && args.editors.length === 0) {
                     editorCount = 0;
-                    scope.editors = [];
+                    scope.editors = [];                    
+                    // Remove the inert attribute from the #mainwrapper
+                    focusLockService.removeInertAttribute();
                 }
             }));