MQTT Topic Hierarchy

With our own MQTT Broker offering now, we are looking to extend value here by displaying the known topic hierarchy for messages being sent to the relevant Team's clients.

## Technical Discussion Points

```[tasklist]
### Pre-requisites
- [x] Establish method for extracting hierarchy
```

```[tasklist]
### Development
- [x] Build API to expose used MQTT topics on Team's Broker (https://github.com/FlowFuse/flowfuse/pull/4748)
- [ ] https://github.com/FlowFuse/flowfuse/issues/4752
```

```[tasklist]
### Followup Tasks
- [ ] https://github.com/FlowFuse/flowfuse/issues/4801
- [ ] https://github.com/FlowFuse/flowfuse/issues/4802
```

### UX Design Phases

#### Phase 1 - Basic View

View-mode only, render the topic hierarchy for the broker. Note that the view now has two tabs: "Hierarchy" and "Clients".