Notification settings checkboxes are not accessible

### Steps to reproduce

1. Launch a screen reader on your platform of choice--any should do.
2. Right-click a room in the rooms tree.
3. Click Settings.
4. Click Notifications.

### Outcome

#### What did you expect?

"Default", "All messages", etc. should be presented to my screen reader as a radio button with only one checked.

#### What happened instead?

Only the text of the options is spoken, with no indication that they are clickable or of which one is selected.

### Operating system

Windows

### Application version

All recent versions

### How did you install the app?

Desktop app

### Homeserver

Synapse, latest

### Will you send logs?

No