Enable Public Sharing of Node-RED Editor

### Epic

https://github.com/FlowFuse/flowfuse/issues/3617

### Description

As a: FlowFuse User

I want to: have the possibility to share my Node-RED Editor publicly via a Link

So that: others with the link can review my flows and help me debug a problem.

### Which customers would this be availble to

Everyone - CE/Starter/Team/Enterprise

### Acceptance Criteria

- [ ] Add an Authentication method "Public" to allow the sharing of Node-RED Editor links.
- [ ] Ensure that users with no FlowFuse account can access the Editor with the correct link, facilitating broader collaboration.
- [ ] Restrict non-FlowFuse users to "Viewer" access only, to maintain the integrity and security of the flows being shared.

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

I have provided an initial effort estimate