add initial marp implementation with sample content and build configuration

node_modules/mj-context-menu/js/sub_menu.d.ts

@@ -0,0 +1,19 @@
+import { AbstractMenu } from './abstract_menu.js';
+import { Submenu } from './item_submenu.js';
+import { ParserFactory } from './parser_factory.js';
+export declare class SubMenu extends AbstractMenu {
+    private _anchor;
+    static fromJson(factory: ParserFactory, { items: its }: {
+        items: any[];
+        id: string;
+    }, anchor: Submenu): SubMenu;
+    constructor(_anchor: Submenu);
+    get anchor(): Submenu;
+    post(): void;
+    protected display(): void;
+    private setBaseMenu;
+    left(_event: KeyboardEvent): void;
+    toJson(): {
+        type: string;
+    };
+}