feat: add welcome page

src/workbench/editor/welcome/index.tsx

@@ -0,0 +1,11 @@
+import { prefixClaName } from 'mo/common/className';
+import * as React from 'react';
+import './style.scss';
+
+export default function Welcome() {
+    return (
+        <div className={prefixClaName('welcome')}>
+            Welcome Page.
+        </div>
+    );
+}

src/workbench/editor/welcome/style.scss

@@ -0,0 +1,9 @@
+@import 'mo/style/const';
+
+#{prefix('welcome')} {
+    align-items: center;
+    display: flex;
+    justify-content: center;
+    text-align: center;
+    width: 100%;
+}