MDL-83257 editor_tiny: Disable Alt+F12 keyboard shortcut

This was introduced in Tiny 7.1 to focus notifications, but it conflicts
with the German keyboard layout which uses Alt+F12 to access the open
curly brace.

This is an upstream problem with TinyMCE and should be fixed in a future
release.

The recommended workaround is to disable the shortcut.

lib/editor/tiny/amd/src/editor.js

@@ -328,6 +328,17 @@ const getStandardConfig = (target, tinyMCE, options, plugins) => {
         // eslint-disable-next-line camelcase
         license_key: 'gpl',
 
+        // Disable the Alt+F12 shortcut.
+        // This was introduced in Tiny 7.1 to focus notifications, but it conflicts with the German keyboard layout
+        // which uses Alt+F12 to access the open curly brace.
+        // This is an upstream problem with TinyMCE and should be fixed in a future release.
+        // The recommended workaround is to disable the shortcut.
+        // See MDL-83257 for further information.
+        // eslint-disable-next-line camelcase
+        init_instance_callback: (editor) => {
+            editor.shortcuts.remove('alt+f12');
+        },
+
         setup: (editor) => {
             Options.register(editor, options);