Refresh Now: Add a message to notify users they are signed out of their Pocket Casts Sync account

### Expected behavior

It would be nice if a small message is shown to notify users that they are signed out when pressing 'Refresh Now', or alternatively remove that button if it serves no purpose when signed out (I assume it might also check for new episodes)

### Actual behavior

The Refresh Buttons works like normal, which doesn't make it clear to users that they are signed out

https://user-images.githubusercontent.com/16253818/198013316-ae827815-0b0b-4378-a043-b73ac2466e7d.MP4

Reported in #5656927-zen

##### Tested on [iPhone 14 Pro Max], iOS [16.1], Pocket Casts [7.25.0.1]

No file or test is named. First reproduce this on the iOS app by signing out and pressing “Refresh Now,” then trace the refresh and account-state entry points. Done means the signed-out state is clearly communicated or the button’s behavior is removed, with the chosen behavior verified on the reported setup.

Written by the indexing model from the issue text.