Do not show config related to inactive transports

The current settings page is pretty scary, and also largely unnecessary if you only have RSS transport active.

If a transport is inactive then the settings related to that transport should not be visible.

Start by locating the settings page and the code that determines which transports are active. Check how RSS and other transport settings are rendered; the work is done when inactive transports' settings are hidden while active transport settings remain visible.

Written by the indexing model from the issue text.