[Task]: Display banner warning while the backend is syncing

### Task description

Chronicle takes hours to sync, and the explorer can provide inaccurate information while chronicle/backend is syncing, it would be a good UX improvement displaying some kind of banner or notification to the user informing that the backend is syncing

If easy to do, we should add it to all networks, if not that easy, lets start with stardust only and then we see for other networks

### Requirements

above mentioned

### Acceptance criteria

above mentioned

### Creation checklist

- [ ] I have assigned this task to the correct people
- [ ] I have added the most appropriate labels
- [ ] I have linked the correct milestone and/or project