Notifications: Disable keyword entry when keywords are set to 'Off'

### Your use case

#### What would you like to do?

To disable the keywords input in "Settings > Notifications > Mentions & keywords" when the notification setting for keywords to 'Off'. Disabling the keyword pills too is desirable.

#### Why would you like to do it?

So I can't cause other bugs related to entering keywords while they are off

#### How would you like to achieve it?

`disabled=true`

### Have you considered any alternatives?

_No response_

### Additional context

Workaround: Toggle the keywords setting back and forth until it behaves.

Consistency with mobile.