chore(ckeditor5-keyboard-marker): port source code

packages/ckeditor5-keyboard-marker/src/kbdui.ts

@@ -0,0 +1,45 @@
+import { AttributeCommand, ButtonView, Plugin } from 'ckeditor5';
+import kbdIcon from '../theme/icons/kbd.svg';
+
+const KBD = 'kbd';
+
+/**
+ * The keyboard shortcut UI feature. It brings a proper button.
+ */
+export default class KbdUI extends Plugin {
+
+	public static get pluginName() {
+		return 'KbdUI' as const;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	init() {
+		const editor = this.editor;
+		const t = editor.t;
+
+		editor.ui.componentFactory.add( KBD, locale => {
+			const command = editor.commands.get( KBD ) as AttributeCommand;
+			const view = new ButtonView( locale );
+
+			view.set( {
+				label: t( 'Keyboard shortcut' ),
+				icon: kbdIcon,
+				keystroke: 'CTRL+ALT+K',
+				tooltip: true,
+				isToggleable: true
+			} );
+
+			view.bind( 'isOn', 'isEnabled' ).to( command, 'value', 'isEnabled' );
+
+			// Execute command.
+			this.listenTo( view, 'execute', () => {
+				editor.execute( KBD );
+				editor.editing.view.focus();
+			} );
+
+			return view;
+		} );
+	}
+}