feat: multiple instances of Molecule

### Description

The Molecule only supports the standalone currently, when you use the `create()` function, it just returns a global `molecule` instance. But some developers need to create multiple instances of Molecule in one page, like:

```ts

const moInstance1 = create({
extensions: [],
});

const moInstance2 = create({
extensions: [],
});

const App1 = () => moInstance.render();

const App2 = () => moInstance2.render();

// Do something
moInstance1.editor. open()
moInstance2.editor. open()

```