Fix browser history when accessing the immersive editor

### Current Behavior

When accessing the immersive editor, multiple instances of the page are pushed into the browser's history causing difficulties when users want to navigate back to the previous page.

### Expected Behavior

Users should one click the back button after accessing the immersive editor

### Steps To Reproduce

Open the immersive editor and check browser history

### Environment

- FlowFuse version: 2.8.0
- Node.js version: N/A
- npm version: N/A
- Platform/OS: N/A
- Browser: N/A

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate