feat: init new plugin system (#3323)

plugins/hello-world/src/app.tsx

@@ -0,0 +1,17 @@
+import { IconButton, Tooltip } from '@affine/component';
+import { AffineLogoSBlue2_1Icon } from '@blocksuite/icons';
+import { useCallback } from 'react';
+
+export const HeaderItem = () => {
+  return (
+    <Tooltip content="Plugin Enabled">
+      <IconButton
+        onClick={useCallback(() => {
+          console.log('clicked hello world!');
+        }, [])}
+      >
+        <AffineLogoSBlue2_1Icon />
+      </IconButton>
+    </Tooltip>
+  );
+};

plugins/hello-world/src/index.ts

@@ -0,0 +1,26 @@
+import type { PluginContext } from '@toeverything/plugin-infra/entry';
+import {
+  currentWorkspaceIdAtom,
+  rootStore,
+} from '@toeverything/plugin-infra/manager';
+import { createElement } from 'react';
+import { createRoot } from 'react-dom/client';
+
+import { HeaderItem } from './app';
+
+export const entry = (context: PluginContext) => {
+  console.log('register');
+  console.log('hello, world!');
+  console.log(rootStore.get(currentWorkspaceIdAtom));
+  context.register('headerItem', div => {
+    const root = createRoot(div);
+    root.render(createElement(HeaderItem));
+    return () => {
+      root.unmount();
+    };
+  });
+
+  return () => {
+    console.log('unregister');
+  };
+};